Which sample of O2 contains a total of 3 x 1023 molecules? ( click image )

Calculate the molar solubility of CaF2 in a 0.25 m solution of NaF(aq).

Kipish [7]

Answer:

6.4 × 10^-10 M

Explanation:

The molar solubility of the ions in a compound can be calculated from the Ksp (solubility constant).

CaF2 will dissociate as follows:

CaF2 ⇌Ca2+ + 2F-

1 mole of Calcium ion (x)

2 moles of fluorine ion (2x)

NaF will also dissociate as follows:

NaF ⇌ Na+ + F-

Where Na+ = 0.25M

F- = 0.25M

The total concentration of fluoride ion in the solution is (2x + 0.25M), however, due to common ion effect i.e. 2x<0.25, 2x can be neglected. This means that concentration of fluoride ion will be 0.25M

Ksp = {Ca2+}{F-}^2

Ksp = {x}{0.25}^2

4.0 × 10^-11 = 0.25^2 × x

4.0 × 10^-11 = 0.0625x

x = 4.0 × 10^-11 ÷ 6.25 × 10^-2

x = 4/6.25 × 10^ (-11+2)

x = 0.64 × 10^-9

x = 6.4 × 10^-10

Therefore, the molar solubility of CaF2 in NaF solution is 6.4 × 10^-10M

8 0

3 years ago

Ammonia and oxygen react to produce nitric oxide and water. Which of the following chemical equations describes this reaction an

aksik [14]

Answer:

Option B. 4NH3(g) + 5O2(g) —> 4NO(g) + 6H2O(g)

Explanation:

The reaction between ammonia, NH3 and oxygen, O2, will produce nitric oxide and water as shown below:

NH3(g) + O2(g) —> NO(g) + H2O(g)

Now, let us balance the equation.

This is illustrated below:

NH3(g) + O2(g) —> NO(g) + H2O(g)

There are 3 atoms of H on the left side and 2 atoms on the right side. It can be balance by putting 4 in front of NH3 and 6 in front of H2O as shown below:

4NH3(g) + O2(g) —> NO(g) + 6H2O(g)

There are 4 atoms of N on the left side and 1 atom on the right side. It can be balance by putting 4 in front of NO as shown below:

4NH3(g) + O2(g) —> 4NO(g) + 6H2O(g)

Now, the are 2 atoms of O on the left side and a total of 10 atoms on the right side. It can be balance by putting 5 in front of O2 as shown below:

4NH3(g) + 5O2(g) —> 4NO(g) + 6H2O(g)

Now, we can see that the equation is balanced.

Therefore, option B gives the balanced chemical equation for the reaction.

5 0

3 years ago

Determine whether each of the descriptions of matter describes a heterogeneous mixture, a homogeneous mixture, or a pure substan

lorasvet [3.4K]

Answer: a. two substances present; two phases present : Heterogeneous mixture

b. two substances present; one phase present : Homogeneous mixture

c. one substance present; one phase present : pure substance.

d. one substance present; two phases present: Heterogeneous mixture

Explanation:

A pure substance is a substance which contains definite composition of only one type of component. Hence, it cannot be separated by physical means.

Mixture is a substance which contains two or more than two types of components and they can be separated by physical means as well.

Homogeneous mixtures: It is a mixture that has uniform composition throughout the solution and the particle size or shapes are not different. There is no physical boundary between the dispersed phase and dispersion medium.

Heterogeneous mixtures: It is a mixture that has non-uniform composition throughout the solution and the particle size or shapes are also different. There is a physical boundary between the dispersed phase and dispersion medium.

5 0

3 years ago

HELP ME ON THIS

diamong [38]

Answer:

The attractive force between them decreases

Explanation:

This is because they become localised.

7 0

3 years ago

If a helium filled ballon has a volume of 3.4l at 25°c and 1.18atm., what is its volume at STP?

vladimir2022 [97]

Answer:

3.711 L

Explanation:

The formula you need to use is the following:

$\frac{V_{1}}{T_{1}} = \frac{V_{2}}{T_{2}}\\$

3.4L / 298 K = V2 / 273 K

V2 = 3.711 L

5 0

2 years ago