Answer:
Explanation:It is given that burning one mole of caffeine gives heat.
The given mass of caffeine is 5g.
Molar mass of caffeine can be calculated as shown below.
Calculate the number of moles of caffeine burned as follows:
Q = mc ΔT
0.0258 ×4.96 × 103 × 284.37
= 3.64 × 104J/°C
When sodium reacts with water.........gas evolves
(O2-CO2-H2-N2)
When sodium reacts with water, hydrogen gas evolves (option C).
What is a chemical reaction?A chemical reaction is a reaction that typically involves the breaking or making of interatomic bonds, in which one or more substances are changed into others.
A chemical reaction combines two or more substances called reactants to form new substances called products.
According to this question, sodium (Na) reacts with water (H2O) as follows:
2Na + 2H₂O → 2NaOH + H₂
As observed in the above chemical reaction, sodium metal reacts with water to produce sodium hydroxide and hydrogen gas.
Therefore, it can be said that hydrogen gas is evolved when sodium combines chemically with water.
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which compound will distill first? group of answer choices the compound with the lower density the compound with the lower boiling point the compound with the higher boiling point the compound with the higher density the compound with the lower molecular weight the compound with the higher molecular weight
Answer:
So, liquid H2 will be distilled first, after this liquid N2 will be distilled, followed by liquid O2 and liquid CO2 will be distilled last.
The compound will lower molecular weight will distill out first as it will evaporate fast.
What is a compound?Compound is defined as a chemical substance made up of identical molecules containing atoms from more than one type of chemical element.
Molecule consisting atoms of only one element is not called compound.It is transformed into new substances during chemical reactions. There are four major types of compounds depending on chemical bonding present in them.They are:
1)Molecular compounds where in atoms are joined by covalent bonds.
2) ionic compounds where atoms are joined by ionic bond.
3)Inter-metallic compounds where atoms are held by metallic bonds
4) co-ordination complexes where atoms are held by co-ordinate bonds.
They have a unique chemical structure held together by chemical bonds Compounds have different properties as those of elements because when a compound is formed the properties of the substance are totally altered.
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The enzyme that catalyzes the synthesis of atp as hydrogen ions flow down their concentration gradient is called.
The enzyme that catalyzes the synthesis of ATP as hydrogen ions flow down their concentration gradient is called ATP synthase.
What is ATP synthase?In the inner mitochondriаl membrаne, hydrogen ions hаve just one chаnnel аvаilаble: а membrаne-spаnning protein known аs АTP synthаse. Conceptuаlly, АTP synthаse is а lot like а turbine in а hydroelectric power plаnt. Insteаd of being turned by wаter, it’s turned by the flow of hydrogen ions moving down their electrochemicаl grаdient. Аs АTP synthаse turns, it cаtаlyzes the аddition of а phosphаte to АDP, cаpturing energy from the proton grаdient аs АTP.
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how many atoms are in 2.5 moles of c4h802
Answer:
1.505 × 10²⁴ atomsExplanation:
To find the number of entities in a given substance we use the formula
N = n × L
where n is the number of moles
N is the number of entities
L is the Avogadro's constant which is
6.02 × 10²³ entities
From the question
n = 2.5 moles
We have
N = 2.5 × 6.02 × 10²³ = 1.505 × 10²⁴
We have the final answer as
1.505 × 10²⁴ atomsHope this helps you
Metals will always form _________________ ions, called _______________.
Answer: 1. Positive ions
2. They're called Cations
explanation: Cations are positive ions and anions are negative ions. Metals always form positive ions as they lose electrons to be like the Nobel gases - with full outer shells.
Consider a 3-atom molecule a-b-a for which b has a total of only two valence electrons. If you assume that b is a group ii metal, what is the bond angle for a-b-a? please answer in degrees to the nearest whole number.
Consider a 3-atom molecule a-b-a for which b has a total of only two valence electrons if you assume that b is a group ii metal, then the bond angle for a-b-a is 180 degree
Valence electron is the s and p electron in the outermost shell and electron present in the inner shell are core electron and according to the valence shell electron pair repulsion theory and we that bond angle that an atom has with its neighbor which also called dihedral angle a group II metal has two valence electron there it can form only single bond then b will not have any lone pair and the ones digit in the group number is the number of valence electron and 180 degree bond angle means the atom are connected in straight line called 180 degree bond
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Alanine is a member of the twenty key amino acids that are used by our bodies to make proteins. Is this a chiral molecule?.
Alanine is a member of the twenty key amino acids which might be used by our bodies to make proteins: Pyrrolysine (not utilized in human protein synthesis). of those 20 amino acids, nine amino acids are crucial: Phenylalanine. Valine. Tryptophan.
Alanine is an amino acid that is used to make proteins. it's miles used to break down tryptophan and diet B-6. it's miles a source of power for muscle mass and the central fearful gadget. It strengthens the immune device and helps the frame use sugars.
Alanine, or α-alanine, is an α-amino acid this is used in the biosynthesis of proteins. It contains an amine organization and a carboxylic acid organization, both connected to the valuable carbon atom which also contains a methyl institution facet chain. Alanine is an amino acid this is used to make proteins. it's miles used to interrupt down tryptophan and diet B-6. it's miles a supply of electricity for muscle tissue and the critical apprehensive gadget. It strengthens the immune system and allows the frame to use sugars.
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In two to three sentences, explain the importance of the following in a nuclear reactor:
control rods
containment structure
a moderator
The importance of the following below in a nuclear reactor are:
Control rods - Reaction maintenance.Containment structure - Protection for the environment.Moderator - slows electrons down.What is a Nuclear reactor?This is referred to as the device which is used to start up and control a fission or fusion nuclear chain reaction or nuclear fusion reactions.
The control rod is responsible for the absorption of neutrons so that the nuclear chain reaction taking place within the reactor core can be slowed or stopped. The containment structure help to prevent rays from getting into the environment thereby serving as a protective factor.
The moderator helps to slow down the speed of neutrons especially in those who have a very high speed thereby making it the correct choice.
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Consider the hydrate calcium chloride dihydrate: cacl2 · 2h2o. how many hydrogen atoms are in the compound?
Consider the hydrate calcium chloride dihydrate hydrogen atoms are in the compound are four
Hydrate calcium chloride dihydrate is the excellent water soluble crystalline calcium sources used compatible with chloride and chloride compounds can conduct electricity when fused or dissolved in water and here given compound is CaCl₂ × 2H₂O
So in that compound the hydrogen atom are four because this compound or this equation is balanced so in that compound four hydrogen atom are present
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Answer:
4
Explanation:
Which weather pattern consists of a low-pressure system of rising warm, moist weather that leads to cloudy and rainy weather?
Cyclone movement
Convection currents
The Coriolis effect
Anticyclone winds
pls help soon
Answer:
Cyclone Movement
Explanation:
To form a cyclone, warm, moist air over the ocean rises upward from near the surface. As this air moves up and away from the ocean surface, it leaves is less air near the surface.
So basically as the warm air rises, it causes an area of lower air pressure below.
What atom matches this electron configuration?
1s22s22p63s2 3p64s23d104p65s24d105p66s24f145d9
Mercury
Thallium
Gold
Platinum
Answer:
Gold
Explanation:
To recognize what element this is, we can simply look at the last orbital (5d9) and go to the periodic table and see what element is in that final orbital.
We go to row 6 (because of the 6s orbital at the beginning of this row) and then we see that our 6s orbital is full with 2 electrons, then our 4f orbital is full with 14 electrons, and our 5d orbital is not full where we only have 9 electrons instead of 10.
We then go to our 5d orbital and count 9 times into that orbital and end up with our final element being Gold (Au).
key questions 1. what distinguishes each of the four examples in illustrating the methodology? 2. why might it be necessary to put double or even triple bonds between atoms in constructing lewis structures? 3. how does the lewis structure help you identify the length of bonds in a molecule? 4. how is formal charge determined, and how is it used in identifying reasonable lewis structures? 5. in the above examples illustrating the methodology, why are relevant resonant structures - present only in the case of no2 ?
An atom's Lewis structure enables you to predict its bonding patterns and number of bonds. We may ultimately be able to comprehend the structures of molecules & their chemical characteristics using this information.
2. The stability of the molecule increases with the number of charges on each element. In order to reduce the number of different formal charges, a double or triple bond should be applied.
3. Dots are used in the Lewis structure to depict the shared electrons between atoms. Next, ascertain whether there is a single, triple, or triple covalent connection between the two atoms. Third, determine the radius of each of the bonded ions based on the type of bond by using an atom radius chart.
4. By considering each bond as if one-half of the electrons were allocated to each atom in a Lewis structure, formal charges can be ascribed to each atom. These fictitious formal charges serve as a reference for selecting the best Lewis structure.
5. N-O bond as well as a double bond. The N atom possesses a positive charge and an unpaired electron. They are the two principal resonance sources of NO2.
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Jane is conducting an experiment on whether different colored light bulbs have an effect on the number of flower buds on a plant. explain how her experiment should be counducted.
The experiment should be conducted by Jane for several days and the observation of each light and its effect on the plant buds should be noted carefully.
To conduct this experiment, first, place a flowering plant in a place that receives that receive optimum sunlight. This is because this experiment is to be conducted at night time to observe the changes in the bud.
The plant should be watered and at the night, the plant should be placed under a colored light say let us take the blue colored light for the first week. The structure and shape of the bud should be noted in the initial time while placing the colored light after sunset and it should be noted before sunrise.
This observation should be noted for a week. For consecutive weeks, the colors of the light should be changed and the same observations are to be noted.
Later, from the observations inferred, the conclusion could be obtained if the plant and its bud have any effect on exposure to colored lights for several weeks.
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a 17.27 gram sample of aluminum initially at 92 oc is added to a container containing water. the final temperature of the metal is 25.1 oc. what is the total amount of energy in joules added to the water? what was the energy lost by the metal?
The heat released by metal and added to water is the same which is 1039.83 joule.
The equilibrium condition of the system depends on the heat released from both gold and water. The total heat received by the system will equal to total heat released by objects. It should follow
Q released = Q received
The heat can be defined by
Q = m . c . ΔT
where Q is heat, m is mass, c is the specific heat constant and ΔT is the change in temperature.
The given parameters are
m = 17.27 g = 0.01727 kf
T1 = 92 ⁰C
T2 = 25.1 ⁰C
c = 900 J/kg⁰C
By substituting the given parameters, we can calculate the heat
Q = m . c . ΔT
Q = 0.01727 . 900 . (92 - 25.1)
Q = 1039.83 joule
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Is the exoplanet like earth in terms of its distance from its star? Explain your answer
The distance between the earth and star = 8 ✕ (9.46 ✕ 1012) = 7.6 ✕ 1013 km.
What is exoplanet?
Every planet in our solar system orbits the Sun. Planets known as exoplanets orbit other stars. It is quite challenging to directly observe exoplanets with telescopes. They are hidden by the bright light from the stars they orbit.
It is challenging to give distances in kilometers for many celestial objects since they are so far away from the earth, such as galaxies or stars.
How far light may travel in a year is measured in large units called light-years. The vast distances are therefore expressed in terms of light-years.
9.46 x 1012 kilometres make up a light year.
In other words, if a star is eight light-years away, light would travel that distance in eight years. This is how the distance between a star and the earth is calculated.
Therefore, the distance between the earth and the star is 8 (9.46 1012) = 7.6 1013 kilometers.
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Eriq, a chemist, is running tests with four unknown elements. He has found that they all bond the same way, so he knows that they are in the same group on the periodic table of elements.
The table shows other properties that Eriq observed.These four elements are most likely in group
15.
16.
17.
18.
Answer:
17
Explanation:
br is liquid
cl is gas
and iodide is solid
How do you determine how many significant figures to report in an addition or subtraction
problem?
Answer:
For addition and subtraction use the following rules:
1. Count the number of significant figures in the decimal portion ONLY of each number in the problem
2. Add or subtract in the normal fashion
3. Your final answer may have no more significant figures to the right of the decimal than the LEAST number of significant figures in any number in the problem.
Explanation:
what are some shared properties of both transition metals and alkali metals.
Both transition metals and alkali metals are good conductors of heat and electricity, react with water, and are easily oxidized.
What are alkali metals and transition metals?The alkali metals are elements of group 1 which are lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr). They are also known as the s-block elements because they have their outermost electron in an s-orbital.
The alkali metals are shiny, soft, highly reactive metals and readily lose their outermost electron to create cations with charge +1. They can tarnish rapidly in the air due to oxidation by atmospheric moisture and oxygen.
Transition elements or transition metals are elements that have partially filled d-orbitals. An element having a d-subshell that is partially filled with electrons or can form stable cations with an incompletely filled d orbital.
Any element present in the d-block of the modern periodic table which consists of groups 3 to 12, is considered to be a transition element. For example, the mercury in the +2 oxidation state, corresponds to an electronic configuration of (n-1)d¹⁰. Many paramagnetic compounds are formed by transition metals because they have unpaired electrons in the d orbital.
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3- Which substance is not a macromolecule?
A diamond
B graphite
C silicon(IV) oxide
D sulfur
Answer:D
Explanation:plato
Simple expriment with Candle that Show the necessary of air far t burining Cansiser how the Scientific method in this Simple experment with air for buring under to d/F Conditions Applies in this necessary
Answer:
use a tumbler to cover a candle that is burning, after a few minutes it turns off automatically without any external forces due to the absence of oxygen
Explanation:
Suppose 57.9 mL of a 0.196 M solution of Na2SO4 reacts with 167 mL of a 0.398 M solution of MgCl2 to produce MgSO4 and NaCl as shown in the balanced reaction.
Na2SO4(aq)+MgCl2(aq)⟶MgSO4(s)+2NaCl(aq)
Calculate the mass of MgSO4 that can be produced in the given reaction.
Only 0.453 g of MgSO4 are isolated after carrying out the reaction. Calculate the percent yield of MgSO4.
The mass of the object obtained is 1.32 g and the percent yield is 34.3%.
What is the amount produced?We know that the reaction equation shows the way the reactants are able to interact so as to obtain the products. We have that;
Number of moles of sodium sulfate = 0.196 M * 57.9/1000 L
= 0.011 moles
Number of moles of magnesium chloride = 0.398 M * 167/1000 L
= 0.066 moles
Given that the reaction is 1:1, the limiting reactant is sodium sulfate
Then;
Mass of the magnesium sulfate produced = 0.011 moles * 120 g/mol
= 1.32 g
The percent yield of the magnesium sulfate = 0.453 g/ 1.32 g * 100/1
= 34.3%
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pyrazole has two nitrogens (labeled 1 and 2). which of the nitrogens will react first with an acid? explain your answer and support it with any relevant structures.
To solve this questions we need to know the heterocyclic compounds and little bit about resonance. Therefore the nitrogen which is labelled 2 will react first with acid.
What is heterocyclic compound?Heterocyclic compounds are those cyclic organic compounds that contains hetero atoms in place of carbon like N,S and O.
Pyrazole contains has structure just like pyrrole the Nitrogen which is labelled 1 that is NH act like nitrogen of pyrrole and the nitrogen that is labelled as 2 act like nitrogen of pyridine.
The electron of NH is involved in resonance, it is not free to give its electron to hydrogen ion from acid. So the nitrogen which is like nitrogen of pyridine will take hydrogen ion from acid first.
Therefore the nitrogen which is labelled 2 will react first with acid.
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which statements correctly describe a polar covalent bond? i. electrons are shared but not equally by the two atoms. ii. one atom has a small negative charge, and the other atom has a small positive charge. iii. the bond dipole is zero. iv. one or more electrons are transferred from one atom to a second atom.
A covalent bond bond is appropriately described as occurring when one or even more electrons move of one atom to another.
what is covalent polar bond?a bond in which the two bound atoms' electron densities are unequally distributed as a result of either a difference in the electronegativity or the effects of induction.
A covalently bonded bond is represented by the water molecule, written as H2O. The oxygen atom is given more time with the electrons than for hydrogen atoms due to the unequal distribution of the electrons.
what is electron?The electron is an unit of matter with a negative zero elementary charge electric charge. Due to their lack of known components, electrons, which are part of the first generation of lepton particles family, are typically regarded to be elementary particles or substructure
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a penny having a mass of 2.5559 g was dissolved in 20 ml of 8 m hno3. the resulting solution was transferred to a 100.00-ml volumetric flask and diluted to the mark with water. this solution was found to have a concentration of 1.06 x 10-2m cu2 . what is the % by mass of copper in the penny?
For a penny having mass 2.5559g dissolved in hno3 and solving from the process as given in the question we get that the penny has 2.64% of copper (Cu) by mass in it
Mass of penny mp = 2.5559g
concentration of Cu in solution = 1.06 * 10^(-2) mol/L
therefore 100ml diluted solution has
n = 1.06*10^(-2) * 100 / 1000 = 1.06 * 10^(-3) mol of copper
The molecular weight of copper mw = 63.5 g/mol
mass of copper Mcu = n * mw(molecular weight of copper)
⇒Mcu = 1.6 * 10^(-3) mol * 63.5 g/mol
⇒Mcu = 0.06731 g
Percentage by mass of copper in the penny, P= (Mcu/ mp)* 100%
⇒ P = (0.06731/2.5559)* 100 %
⇒P = 2.64%
∴There is 2.64% copper by mass in the penny
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unit 3 balancing lab chemistry
HELP PLEASEEEEEEE
1. zn___AgCI->___ZnCI2+___Ag
2. FeCI3+___H2s->___FeCI2+___HCI+___s
3. ___Ag2O->___Ag+___O2
4.AI2O3->___AI+___O2
5.K+___H2O->___KOH+___H2
6. Caco3->___CaO+___CO2
7. MG+___O2->Mgo
8. CO+___Fe2O3->___Fe+___CO2
9. H2+___Fe2O3->___Fe+___H2O
10. ___HCI+ZN->___H2+___ZnCI2
zn + 2 AgCI-> ZnCI2+ 2Ag
2 FeCI3+ 3 H2s->___FeCI2+ 6 HCI+___s
2 Ag2O-> 4 Ag+ O2
4AI2O3-> 3 AI+ 2O2
2 K+ 2H2O-> 2 KOH+ H2
Caco3-> CaO+ CO2
2 MG+ O2-> 2MgO
CO+ 3 Fe2O3-> 2 Fe+ 3CO2
2 H2+ 3 Fe2O3-> Fe+ 3H2O
HCI+ 2 ZN-> H2+ ZnCI2
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9. running a strong enough electric current through water will cause it to decompose into hydrogen and oxygen gas. write the balanced chemical equation for this process. what is being oxidized, and what is being reduced?
Answer:
Explanation: when electric current is passed through water, water dissociates into hydrogen and oxygen. Hydrogen is deposited over negative pole and oxygen is deposited over positive pole. Deposition of hydrogen and oxygen at different poles is visible in the form of bubbles.
a mineral compound is composed of mn and o. if 77% of the mass of the mineral compound is due to manganese, what is the empirical formula of the mineral compound?
Answer:
MnO
Explanation:
See the attachwed worksheet
Synthetic materials are not found in nature and therefore they are typically developed in laboratories.
True
False
Answer: True
Explanation: Synthetic materials are not found in nature and can be created in labs using chemicals and compounds.
if use a sepratory funnel containing a phenol with methylene chloride and an nahco3, where will the phenol be located? the answer is organic and bottom layer, but why is that and how do we answer similar questions?
phenol does not react with NaHCO3 , phenol solubility in water is very less about 8g in 100mL of water , so it will be present in organic layer (methylene chloride) , methylene chloride has a density of 1.33g/mL greater than water so it will be below layer in which phenol is present.
What is the function of separatory funnel?Immiscible liquids are separated using a separatory funnel, or sep funnel. Two layers appear in a separatory funnel when two immiscible liquids are added. The lower layer will be made up of the denser solvent. Most halogenated solvents are less dense than water, but most non-halogenated solvents are.
A separating funnel is used by adding the two phases and the mixture to be separated via the top while keeping the stopcock at the bottom closed. After then, the funnel is shut and gently shaken by being inverted several times. If the two solutions are combined too vigorously, emulsions will form.
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Why was temperature change for the water slight in your experiments while the temperature change for the metal was large?.
Temperature change for water was slight compared to temperature change in metal because of specific heating capacities.
Specific heat capacity, moreover, known basically as specific heat, is the degree of the warm vitality required to extend the temperature of a unit amount of a substance by a certain temperature interim.
Regularly, the metal pole would be much hotter than the water. So, the conclusion can be made that the particular warm of metal is lower than the particular warm of water.
It requires less warm per unit mass to form a more noteworthy alteration in temperature for metal than it does for water.
Specific heat is additionally some of the time alluded to as heat capacity.
Casually, it is the sum of warm that must be included in one unit of mass of the substance in arrange to cause an increment of one unit in temperature. The SI unit of particular warm capacity is joule per kelvin per kilogram, J⋅kg −1 ⋅K −1.
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