Quiz | Chemical Calculations for Solutions

1

Which of the following factors affects the solubility of a particular substance?

Temperature

Nature of solute

Solvent

All of the above

Solubility is the maximum quantity of solute dissolvable in a solvent at a particular temperature. A solid is more soluble at higher temperatures and in a solvent with similar types of intermolecular forces

2

What is the molarity of a solution that contains 8 moles of solute in 2 liters of solution?

M

M

10 M

16 M

Molarity M  =  nsoluteVsolution  =  84  =  4M

3

What is the mass of NaCl in 250 mL of a 0.4 M solution?

0.1 g

5.84 g

36.5 g

93.4 g

number of moles nNaCl  =  M x Vsolution  =  mNaClMNaCl  

⇒ mNaCl  = M x Vsolution x MNaCl   with MNaCl = molar mass of NaCl = MNa + MCl = 23.0 + 35.4 = 58.4 g.mol-1

⇒ mNaCl  = 0.4 x 0.250 x 58.4 = 5.84 g

4

What does not change when a solution is diluted by the addition of solvent?

Molarity of solution

Mass of solvent

Number of moles of solute

Volume of solvent

 In dilution, the amount of solute does not change: the number of moles are the same before and after dilution

5

How many mL of a 2.0 M NaBr solution are needed to make 300.0 mL of 0.5 M NaBr?

25 mL

30 mL

75 mL

300 mL

In dilution, the amount of solute does not change: n1 = n2 ⇒ M1 x V1 = M2 x V2
2.0 x V1 = 0.5 x 0.300 ⇒ V1 = 0.075 L = 75 mL

6

What is the endpoint of a titration?

When the pH of the solution is < 7

When the pH of the solution is > 7

When the volume of the solution with a known concentration in the burette is used up

When the amount of acid and base are equal as shown by a color change of the indicator