Silicon has three naturally occurring isotopes with thefollowing masses and natural abundances:
Isotope Mass ({\rm amu}) Abundance (%)
{\rm Si}-28 27.9769 92.2
{\rm Si}-29 28.9765 4.67
{\rm Si}-30 29.9737 3.10
Calculate the atomic mass of silicon.
b- When solutions of silver nitrate and calcium chloride aremixed, silver chloride precipitates out of solution according tothe equation
2\; \rm AgNO_3 \it (aq) \rm \;+\;CaCl_2 \it (aq) \rm \; \rightarrow \; 2\;AgCl \it (s) \rm\; + \; Ca(NO_3)_2 \it (aq)
What mass of silver chloride can be producedfrom 1.18 L of a 0.113 \it M solution of silver nitrate?
The reaction described required3.28 L of calcium chloride. What is the concentration of thiscalcium chloride solution?
c- A volume of 50.0 mL of aqueous potassium hydroxide (\rm KOH) was titrated against a standard solution of sulfuricacid (\rm H_2SO_4). What was the molarity of the \rm KOH solution if 23.7 mL of 1.50 M\rm H_2SO_4 was needed? The equation is
\rm 2KOH(\it aq\rm )+H_2SO_4(\it aq\rm )\rightarrow\rm K_2SO_4(\it aq\rm )+2H_2O(\it l\rm )
Then, Redox titrations are used to determine the amounts ofoxidizing and reducing agents in solution. For example, a solutionof hydrogen peroxide, \rm H_2O_2, can be titrated against a solution of potassiumpermanganate, \rm KMnO_4. The following equation represents the reaction:
\matrix{{\rm 2KMnO}_4(aq)+{\rm H_2O}_2(aq)+3{\rm H_2SO}_4(aq)\rightarrow&&\hfill\cr\hfill \qquad\qquad\qquad{\rm O}_2(g)+2{\rm MnSO}_4(aq)+{\rm K_2SO}_4 (aq)+4{\rm H_2O}(l)&&\hfill}
A certain amount of hydrogen peroxide was dissolved in 100.\rm mL of water and then titrated with 1.68 M\rm KMnO_4. How much \rm H_2O_2 was dissolved if the titration required13.8 mL of the \rm KMnO_4 solution?

Answer:

157 g of MgO

Explanation:

the reaction:

2Mg + O2 ➡️ 2MgO

1) find the mol of Mg

mol = mass / molar mass

mass = 94.2 g

molar mass = 24

mol = 94.2 / 24

mol = 3.925 mol

2 mol = 3.925 moles

2) find mass of MgO

mass = mol × molar mass

mol = 3.925

molar mass = 24+16 = 40

mass = 3.925 × 40

= 157 g

Answer:

The answer is Ytterbium but it is one of it isoptoped so techniacally it would be Ytterbium 102.

Answer:

2.99 mol

Explanation:

Number of moles of CO₂ = ?

Volume = 67 L

Temperature and pressure = standard

Solution:

The given problem will be solve by using general gas equation,

PV = nRT

P= Pressure

V = volume

n = number of moles

R = general gas constant = 0.0821 atm.L/ mol.K  

T = temperature in kelvin

By putting values,

1 atm × 67 L = n ×0.0821 atm.L/ mol.K × 273.15 K

67 atm.L = n×22.43 atm.L/ mol

n = 67 atm.L/22.43 atm.L/ mol

n = 2.99 mol

Answer:

21.5 g.

Explanation:

Hello!

In this case, since the reaction between the given compounds is:

[tex]2Li_3P+Al_2O_3\rightarrow 3Li_2O+2AlP[/tex]

We can see that according to the law of conservation of mass, which states that matter is neither created nor destroyed during a chemical reaction, the total mass of products equals the total mass of reactants based on the stoichiometric proportions; in such a way, we first need to compute the reacted moles of Li3P as shown below:

[tex]n_{Li_3P}^{reacted}=38gLi_3P*\frac{1molLi_3P}{51.8gLi_3P}=0.73molLi_3P[/tex]

Now, the moles of Li3P consumed by 15 g of Al2O3:

[tex]n_{Li_3P}^{consumed \ by \ Al_2O_3}=15gAl_2O_3*\frac{1molAl_2O_3}{101.96gAl_2O_3} *\frac{2molLi_3P}{1molAl_2O_3} =0.29molLi_3P[/tex]

Thus, we infer that just 0.29 moles of 0.73 react to form products; which means that the mass of formed products is:

[tex]m_{Li_2O}=0.29molLi_3P*\frac{3molLi_2O}{2molLi_3P} *\frac{29.88gLi_2O}{1molLi_2O} =13gLi_2O\\\\m_{AlP}=0.29molLi_3P*\frac{2molAlP}{2molLi_3P} *\frac{57.95gAlP}{1molAlP} =8.5gAlP[/tex]

Therefore, the total mass of products is:

[tex]m_{products}=13g+8.5g\\\\m_{products}=21.5g[/tex]

Which is not the same to the reactants (53 g) because there is an excess of Li₃P.

Best Regards!

Answer:

Explanation:

From the information given:

Molecular weight Mi      Number of chains (Ni)      NiMi

400                                           6500                        2600000

1000                                         10000                       10000000

8                                               1000000                   8000000

[tex]\sum_{Ni} = 1408[/tex]                                                [tex]\sum _{NiMi}[/tex] = 20600000

Thus, the average number of molecular weight = [tex]\dfrac{\sum_{NiMi}}{\sum_{Ni} }[/tex]

[tex]= \dfrac{20600000}{1408}[/tex]

= 14630.68

b)

weight-average molecular weight  = [tex]\dfrac{\sum _{NiMi^2} }{\sum _{NiMi}}[/tex]

[tex]Ni[/tex]                  [tex]Mi[/tex]             [tex]Mi^2[/tex]                     [tex]Ni[/tex] [tex]Mi^2[/tex]

400              6500          42.25 × 10⁶        16.9  × 10⁹

1000             10000        100 × 10⁶            100 × 10⁹

8                   1000000    1 × 10¹²               800 × 10⁹

                                                                [tex]\sum _{NiMi^2} = 916.9 \times 10^9[/tex]

weight-average molecular weight   [tex]=\dfrac{916.9 \times 10^9 }{20.6 \times 10^6}[/tex]

= 44509.71

c)

The number average molecular weight is most significantly affected. This is because the number average molecular weight value is worth more in comparison to the weight-average molecular weight.

d)

The polydispersity index (PI) = [tex]\dfrac{\overline {M_W}}{\overline {M_n}}[/tex]

[tex]PI = \dfrac{44509.71}{14630.68}[/tex]

PI = 3.04

Explanation:

Displacement is the distance travelled in a specific direction. Unlike distance, displacement is a vector quantity with both magnitude and directional attribute.

When we specific displacement values, we must indicate the direction of motion to complete its description.

For example, 50m is a distance value. It has a magnitude but no direction.

When we say 50m due south, this is a displacement because both magnitude and direction are accurately specified and defined.

During a chemical reaction nb of atoms and mass is always conserved , so mass of Reactants is equal mass of Products.

Answer:

Gamma Rays

Explanation:

Hope it helps!! :))

Tell me if im wrong.

Answer:

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Explanation:

Answer: Energy transfer would occur only between the copper bars and the surroundings.

Explanation:

It should be noted that in the open system, there is transfer of both energy and mass from the system and also into the system as well.

Assuming the bars were in an open system, the transfer of energy would occur only between the copper bars and the surroundings.

Explanation:

In an isolated system, two copper bars at different temperatures transfer energy until both are at the same temperature. How would the transfer of energy be different if the bars were in an open system?

A.

Energy transfer would occur only between the copper bars.

B.

Energy transfer would occur between the copper bars and the surroundings.

C.

No energy transfer would occur between the copper bars or the surroundings.

D.

Energy transfer would occur only with the surroundings.

Answer:each of a number of concentric rings in the cross section of a tree trunk, representing a single year's growth.

Explanation:it tell whats the age of the tree.

Answer:

The correct answer is A)

Explanation:

An NMR or Nuclear Magnetic Resonance Spectrometer is an equipment that can be used to study the nature of molecules after their nuclei have been excited with the use of radio waves. Radio waves generated is converted into nuclear magnetic resonance.

The resonance produced can be recognized or decoded by special radio receivers.  

Besides recognizing the molecular structure of a chemical compound, it's purity and its content can also be analyzed.

Cheers!

Answer:

Can you get a closer picture, then I can help! It looks like it says something on rain, hail and something else. I cant see it though! :)

Explanation:

Answer:

5162.539 g

Explanation:

Let assume that the volume changes from [tex]4.00 \times 10^6 \ L[/tex] to [tex]4.50 \times 10^6 \ L[/tex].

And if the addition of energy as heat is [tex]1.3 \times 10^8 \ J[/tex]

Then; we can say that the total heat that is taken by the ballon = [tex]1.3 \times 10^8 \ J[/tex]

[tex]= 1.3 \times 10^5 \ kJ[/tex]

The total heat supplied = total heat coming from the combustion of propane

∴

[tex]= \dfrac{100}{50} \times 1.3 \times 10^5 \ kJ[/tex]

[tex]= 2.6 \times 10^5 \ kJ[/tex]

[tex]C_3 H_{8(g)} + 5O_{2(g)} \to #CO_{2(g)} + 4H_2O_{(l)} \ \ \Delta H = -2221 \ kJ[/tex]

If 2221 kJ is produced as a result of the combustion of 44.1 g [tex]C_3H_{8(g)}[/tex]

Then;

[tex]2.6 \times 10^5 kJ[/tex] will produce [tex]= \Big( \dfrac{44.1 \times 2.6 \times 10^5}{2221} \Big ) \ g[/tex]

= 5162.539 g

Thus, the mass of the propane that must be burned = 5162.539 g

Mass of Mercury(Hg) : 55.8 g

Given

Reaction

2HgO ⇒ O₂ + 2Hg

Required

Mass of Mercury

Solution

Conservation of mass applies to a closed system, where the masses before and after the reaction are the same

So mass of reactants = mass of products

Mass of reactants = mass HgO = 60 g

Mass of products = mass O₂ + mass Hg

60 g = 4.2 g + mass Hg

mass Hg = 60 - 4.2

mass Hg = 55.8 g

Answer:

yes.it depends on acceleration due to gravity,weight .

Answer:  Light is a transverse, electromagnetic wave that can be seen by the typical human. The wave nature of light was first illustrated through experiments on diffraction and interference

Explanation:

Answer:

Light energy

Explanation:

Answer:

1.Get a ice cub tray.

2. fill cold water to the top.

3. Put the tray in the freezer.

4 let them sit for 3-4 hours.

5.Enjoy!

Explanation:

Answer:

put hotdogs in water boil em. put the water in the cube thingy and put it in the freezer

Answer: The volume of a saturated solution of X in water that would contain 34.0g of X  is 43.9 ml

Explanation:

Solubility is defined as the amount of solute dissolved per 100 ml of the solvent at a fixed temperatur.

Given :  solubility of ionic compound X  in water at [tex]15^0C[/tex] = 0.776 g/ml

0.774 g of X is contained in = 1 ml

Thus 34.0 g g of X is contained in = [tex]\frac{1}{0.774}\times 34.0=43.9 ml[/tex]

Thus the volume of a saturated solution of X in water that would contain 34.0g of X  is 43.9 ml

Answer:

More bro

Explanation:

Pollution is only increasing

Answer: Yes and no, no because people are constantly polluting the earth with plastic which is a big issue.  Yes, because things are being invented to help with plastic pollution, and there is a great number of people who recycle, so however you look at it there's really a 50/50 chance.

Explanation:

cutting a piece of paper

Explanation:

Answer:

A physical change occurs when a substance changes, but no new substance is formed.

Explanation:

Mass of Aluminum= 8.829 g

Given

Reaction

2Al + 6HCl → 2AlCl₃ + 3H₂

Required

mass of Aluminum

Solution

At STP, 1 mol gas = 22.4 L

For 11 L of Hydrogen :

= 11 : 22.4

= 0.491

From equation, mol ratio Al : H₂ = 2 : 3, so mol Al :

= 2/3 x mol H₂

= 2/3 x 0.491

= 0.327

Mass Aluminum(Ar=27 g/mol) :

= 0.327 mol x 27 g/mol

= 8.829 g

The balanced equation :

2Al₂O₃⇒ 4Al+3O₂

Given

Reaction

Al₂O₃⇒ Al+O₂

Required

Balanced equation

Solution

A chemical reaction is said to be balanced if the number of elements involved in the reaction is the same (either the reactants or the products)

The reaction above is said to be unbalanced because the number of elements Al and O in the reactants and products is not the same.

The balancing step

1. Give a coefficient

Al₂O₃⇒ aAl+bO₂

2. Make an equation

Al, left = 2, right = a⇒a=2

O, left = 3, right = 2b⇒2b=3⇒b=3/2

The equation becomes :

Al₂O₃⇒ 2Al+3/2O₂ x2

2Al₂O₃⇒ 4Al+3O₂

Answer:

When carbon dioxide reacts with water carbonic acid is formed, from which hydrogen ions dissociate increasing the acidity of the systemCarbon dioxide emissions to the atmosphere can therefore increase the acidity of land, sea and air

Explanation: