Unit 11 Worksheets: Solution Chemistry

Pure Substances and Mixtures

Substance / Element / Compound / Homogeneous Mixture (solution) / Heterogeneous Mixture / Can it be physically separated? / Can it be chemically separated?
Water
Calcium
Vinegar (water + acetic acid)
Trail mix

Classify each of the following substances and identify whether it can be physically/chemically seperated

  1. For a solution of iodine dissolved in ethanol, which is the solute? Which is the solvent?

Iodine is the solute, ethanol is the

  1. HCl is a polar compound. Will it dissolve in water or oil?
  1. Benzene is a nonpolar compound. Will it dissolve in water or oil?
  1. Do you think sugar is a polar or nonpolar compound? Explain why.

a polar compound because it dissolves in water.

Solutions

  1. Describe three methods to increase the rate of dissolution for sugar in a cup of tea.

the to increase its surface

  1. Explain the difference between rate of dissolution and solubility. Solubility describes how much of a solute can dissolve at a given temperature.
  2. How can you increase the solubility of a solid solute?

Heating the solution usually increases the solubility of a solid solute.

  1. Name two things that increase the solubility of a gaseous solute and name two things that decrease:
  2. Increase:
  3. Decrease:g the temperature and \\
  4. What effect do agitation and surface area have on solubility? and surface area have no effect on solubility. They only affect rate of dissolution.
  5. Of saturated, unsaturated and supersaturated, which word describes a solution with the maximum amount of dissolved solute for a given temperature? Which is less than the maximum? Which is more than the maximum?
  1. How is it possible to dissolve more than the maximum amount of solute for a given temperature?
  1. What happens to a supersaturated solution if it is disturbed?

Solubility Curves

Answer the following questions based on the solubility curve below.

  1. Which salt is least soluble in water at 20°C?

KClO3

  1. Which salt is least soluble at 50°C?

Ce2(SO4)3

  1. How many grams of KCl can be dissolved in 100 g of water at 80°C?

50 g

  1. At 40°C, how much KNO3 can be dissolved in 100 g of water?

60 g

  1. Which salt shows the least change in solubility from 0° to 100°C?

NaCl

  1. At 30°C, 90 g of NaNO3are dissolved in 100 g of water. Is this solution saturated, unsaturated or supersaturated?

unsaturated

  1. A saturated solution of KClO3 is preparedin 100 g of water at 80°C. If the saturated solution is rapidly cooled from 80°C to 50°C, how many grams of precipitate are formed?

20 g

  1. Which two compounds show a decrease in solubility from 0°C to 100°C?

NH3 and Ce2(SO4)3

  1. Above what temperature does KClO3 become more soluble than NaCl?

80°C

  1. A student wishes to prepare a supersaturated solution of 60 g NH4Cl in 100 g water at 50°C. To what temperature must the student heat the solution to dissolve the NH4Cl before cooling it to 50°C?

70°C

  1. If the supersaturated solution from the previous question is disturbed, how many grams of NH4Cl will crystallize out?

10 g

Molarity

The answer for each problem is given in parentheses. YOU MUST SHOW YOUR WORK TO GET CREDIT.

  1. What is the molarity of a solution in which 2.51 mol NaCl are dissolved in 0.585 L of solution? (Ans. 4.29 M NaCl)
  1. How many moles of KNO3 should be used to prepare 2.00 L of a 0.500 M solution? (Ans. 1.00 mol KNO3)

mol = (0.500 M)(2.00 L) = 1.00mol = (0.10 M)(0.10 L) = 0.010 mol CuSO4

  1. To what volume should 0.0667 mol of KCl be diluted in order to prepare a 0.250 M solution? (Ans. 0.267 L solution)

Solubility Rules

Use the solubility chart in your notes or on the reference sheet to determine if the following compounds are soluble in water. Write the solubility rule that explains why the compound is soluble or insoluble.

Compound / Soluble or insoluble? / Why?
strontium sulfate / insoluble / Sulfates are usually soluble, but strontium is an exception.
magnesium nitrate / soluble / Nitrates are soluble. There are no exceptions.
lithium sulfide / soluble / Sulfides are usually not soluble, but akali metals (lithium) are exceptions.
aluminum iodide / soluble / Iodides are usually soluble. Aluminum is not an exception.
silver bromide / insoluble / Bromides are usually soluble, but silver is an exception.
potassium chloride / soluble / Chlorides are usually soluble. Potassium is not an exception.

Electrolytes

Determine which of the following compounds are electrolytes. Write dissociation reactions for the electrolytes.

Compound / Ionic or
Covalent? / If ionic:
soluble or
insoluble? / If ionic and soluble: electrolyte / If electrolyte: dissociation reaction / Number
of ions
CaBr2 / ionic / soluble / electrolyte / CaBr2Ca2+ + 2 Br- / 3
KOH / ionic / soluble / electrolyte / KOHK+ + OH- / 2
AgI / ionic / insoluble
Al2(SO4)3 / ionic / soluble / electrolyte / Al2(SO4)32Al3++3SO42- / 5
H2O / covalent

Fill in the Blank:

  1. ______will determine what substance will layer on top of another substance for

______liquids

  1. ______liquids are able to dissolve freely in one another
  1. ______are insoluble solids that collect at the bottom of a solution
  1. Water is different from other substances because it is ______dense as a liquid and _____ dense as a solid
  1. Water is known as the ______solvent because it’s polarity allows so many substances to dissolve in it
  1. The cohesion of water molecules creates a condition called ______
  1. ______means that there are partial positive and partial negative charges in the molecule
  1. Water is found in groups of 5 because of ______

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