Salt dissolved in water is a mixture.

Answer: Homogeneous (uniform composition throughout) Solutions are homogeneous mixtures. Sand in water is heterogeneous.

In a saltwater solution,

Answer: Water is the solvent (the dissolving medium); salt is the solute Solvent: medium that dissolves; solute: substance dissolved. Usually the substance present in larger amount is the solvent.

A strong electrolyte in solution

Answer: Fully dissociates into ions, conducting electricity well Strong electrolytes: most ionic compounds (NaCl), strong acids (HCl), strong bases (NaOH). Weak electrolytes: weak acids/bases. Non-electrolytes: e.g., sugar.

AP Chemistry · Topic 3.7

Solutions and Mixtures Practice

Part of Properties of Substances and Mixtures.(SPQ-3.A)

Practice questions

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Sample questions

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Sample 1difficulty 1/5
$Salt dissolved in water is a _______ mixture.$
- A
  $Compound$
- B
  $Element$
- C
  $Heterogeneous$
- D
  $Homogeneous (uniform composition throughout)$
  check_circle
Why
$Solutions are homogeneous mixtures. Sand in water is heterogeneous.$
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Sample 2difficulty 1/5
$In a saltwater solution,$
- A
  $Both are solutes$
- B
  $Neither is a solute$
- C
  $Water is the solvent (the dissolving medium); salt is the solute$
  check_circle
- D
  $Salt is the solvent$
Why
$Solvent: medium that dissolves; solute: substance dissolved. Usually the substance present in larger amount is the solvent.$
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Sample 3difficulty 2/5
$A strong electrolyte in solution$
- A
  $Does not dissociate$
- B
  $Forms a precipitate$
- C
  $Partly dissociates$
- D
  $Fully dissociates into ions, conducting electricity well$
  check_circle
Why
$Strong electrolytes: most ionic compounds (NaCl), strong acids (HCl), strong bases (NaOH). Weak electrolytes: weak acids/bases. Non-electrolytes: e.g., sugar.$
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Sample 4difficulty 3/5
$Adding salt to ice melts it because$
- A
  $Salt is hot$
- B
  $Salt creates light$
- C
  $Salt absorbs heat$
- D
  $Solute lowers the freezing point of water below the ambient temperature$
  check_circle
Why
$Why we salt icy roads. ΔT_f = K_f \cdot m \cdot i. Each NaCl gives i = 2 dissolved particles.$
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Sample 5difficulty 3/5
$Adding salt to water _______ its boiling point because$
- A
  $raises; ions disrupt vapor pressure equilibrium, requiring higher T to boil$
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- B
  $doesn't change$
- C
  $lowers; salts evaporate$
- D
  $lowers; less heat is needed to boil$
Why
$Solute lowers vapor pressure \to must heat to higher T for vapor pressure to reach 1 atm. ΔT_b = K_b \cdot m \cdot i.$
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