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Assignment Book
1. How is a chemical reaction that establishes equilibrium different than a quantitative reaction?
2. When given a balanced chemical equation, how can one immediately recognize if the system is at equilibrium?
3. What are the four conditions that must be met in order for a system to be at equilibrium?
4. Explain the collision-reaction theory.
5. What is a macroscopic property? Provide examples.
1. Predict the direction of the equilibrium shift for each of the following changes for the following reaction:
a. Oxygen is added to the system.
b. The temperature of the system is increased.
c. Nitrogen monoxide is removed from the system.
d. The pressure of the system increased by decreasing the volume.
2. For each of the following chemical system at equilubrium, use Le Chateliers principle to predict the effect of the change imposed on the chemical system.
Indicate the direction in which the equlibrium is expected to shift.
a.
b.
c.
d.
3. For each chemical reaction in question 2, sketch a graph of concentrations vs. time for what each change would look like.
4. The following chemical equilibrium, system is part of the Haber process for the production of ammonia:
Predict five specific changes that you can impose on the equilibrium to increase the amount of ammonia produced.
5. Identify the stresses that occurred at time A, B, C, and D
A______
B______
C______
D______
6. For the following equilibrium system, explain how the system will shift when the following stresses are imposed:
ΔH = negative
a. Methane is added
b. The container volume increases
c. The temperature is lowered
d. A catalyst is added to the system
1. Define Kc.
2. The only variable that influences Kc is a change in ______.
3. Write the balanced chemical equation with whole number coefficients and the equilibrium law expression for the following:
a. Hydrogen gas reacts with chlorine gas to produce hydrogen chloride gas.
b. In the Haber process, nitrogen gas reacts with hydrogen gas to produce gaseous ammonia.
c. Carbonic acid decomposes into liquid water and carbon dioxide gas.
4. What is meant by reactants or products being favoured?
5. If the percent yield for a reaction was 40%, explain whether reactants or products would be favoured.
6. If a percent yield for a reaction was greater than 99.9%, explain whether reactants or products would be favoured.
7. The larger the Kc value the more ______are favoured.
8. The smaller the Kc value the more ______are favoured.
1. After 4.0 mol of ethene gas and 2.50 mol of Br2 (g) are placed in a sealed container, the following reaction established an equilibrium:
C2H4 (g) + Br2 (g) C2H4Br2 (g)
The following graph shows the concentration of C2H4 (g) as it changes over time at a fixed temperature until equilibrium is reached.
a. Create an ICE table to solve for the equilibrium concentrations of all reactants and products.
b. Draw lines on the above graph to show how the concentration of each of the other two substances changes.
c. What is the volume of the container?
2. 4.00 mol/L of nitrogen gas and hydrogen gas are placed in a reaction vessel. If 2.50 mol/L of ammonia is found at equilibrium, determine the equilibrium concentrations of the reactants.
3. Interpret the following graph to answer these next questions:
Hydrogen and Iodine are placed in a reaction vessel, which was then sealed and heated to 450 degrees Celsius.
a. All three substances are gases. If the container has a volume of 2.00 L, what chemical amount of iodine and hydrogen was present initially?
b. What chemical amount of HI is present at equilibrium?
4. In the Haber process for synthesizing ammonia gas from nitrogen and hydrogen, the value of Kc is 6.0 x 10-2 for the reaction at 500 degrees Celsius.
In a sealed container at equilibrium, the concentration of hydrogen and nitrogen are 0.50 mol/L and 1.50 mol/L respectively.
Calculate the equilibrium concentration of ammonia.
5. To a heated reaction vessel with a volume of 1.00 , Mrs. Leinweber adds 6.23 mmol of H2 (g), 4.14 mmol of I2 (g), and 22.40 mmol of HI (g).
At equilibrium it is determined that that concentration of iodine vapour is 2.58 mmol/L.
Determine the value of Kc for this reaction and state whether reactants or products are favoured.
6. Consider the following reaction: 2HBr (g) H2 (g) + Br2 (g)
Initially 0.25 mol of hydrogen and 0.25 mol of bromine are placed into a 500 mL vessel. Kc for the reaction is 0.020.
Find the concentrations of all reactants and products at equilibrium, and state whether reactants or products are favoured.
7. The pH of a 1.00 mol/L solution of acetic acid is carefully measured to be 2.38 at SATP. What is the value of Ka for acetic acid?
8. Predict the hydronium ion concentration and pH for a 0.200 mol/L aqueous solution of methanoic acid.
9. A student measures the pH of a 0.250 mol/L solution of aqueous ammonia and finds it to 11.32. Calculate the Kb for ammonia.
10. Find the hydroxide ion amount concentration, pOH, pH and the percent reaction (ionization) of a 1.20 mol/L solution of baking soda.
1. Explain the difference between a Bronsted-Lowry Acid and a Bronsted-Lowry Base.
2. Write a Bronsted-Lowry Equation to explain that the following entities are acids
a. HCl(aq)
b. HOOCCOOH(aq)
c. CH3COOH(aq)
d. HPO42-(aq)
3. Write a Bronsted-Lowry Equation to explain that the following entities are bases
a. NH3(g)
b. OCl-(aq)
c. CN-(aq)
d. HPO42-(aq)
4. Classify each reactant as a Bronsted-Lowry acid or base.
a. HF(aq) + SO32-(aq) F-(aq) + HSO3 -(aq)
b.
5. Which reaction predominates when NaHCO3(s) is dissolved in water to produce HCO3-(aq) solution? Will the solution be acidic or basic?
6. Predict the acid-base reaction that occurs, including the position of equilibrium when the following substances are mixed
a.
b.
7. Explain why the indicator Bromothymol blue is yellow when mixed with an acid and blue when mixed with a base using a Bronsted-lowry equation
1.
2.
3.
1.
a.
b.
2. What is a buffer ? Using an example, explain how a buffer system works.
1. List the three necessary pieces of glassware for a titration analysis and explain the uses of each.
2. Explain the difference between an endpoint and equivalence point.
3. Explain the shape of a pH curve and a buffering region on a pH curve. Make a sketch to help illustrate your answer. Label the equivalence point on your sketch.
4. For the following pH curves, answer the following questions:
a. is the sample an acid or base?
b. what is the pH at the equivalence point?
c. what would be an appropriate indicator to use?
d. what volume of titrant was added at the equivalence point?
5. Explain how one can tell if the sample is a strong or weak acid when given a pH curve.
6.
The above is the pH curve for the addition of 0.48 mol/L of sodium hydroxide to 25.0 mL of 0.49 mol/L of acetic acid.
a. Estimate the pH at the equivalence point.
b. Choose an appropriate indicator for this titration.
c. Circle the buffer region on this graph.
d. Identify the species present at the buffer region.
e. Write the Bronsted-Lowry equation for this titration analysis.
7. A sodium phosphate solution is titrated with hydrochloric acid.
a. Identify the reactions that occur at the equivalence points.
b. Why are there only two equivalence points?
c. Write the net equation for this reaction.
1. Complete the following table on the properties of acids and bases.
Properties of Acids / Properties of BasesTaste
Electrolyte or Non-electrolyte?
Effect on Litmus
Dissociate or Ionize?
Relative pH value
Reacts with metals to produce H2 (g) ?
Produces OH- or H3O+ in solution?
2. a. Name the 6 strong acids? Explain where these acids are found in your Data Book.
b. To what degree do strong acids ionize?
3. a. Where are weak acids located in your data book?
b. To what degree do weak acids ionize?
4. What is the relationship between initial strong acid concentration and H3O+ concentration?
5. If hydrochloric acid has a concentration of 12.0 mol/L, what is the initial concentration of its hydronium ions?
6. If a solution has a higher hydronium concentration than hydroxide concentration, is the solution acidic or basic?
7. If a solution has an equal hydronium concentration to its hydroxide concentration, is the solution acidic or basic?
8. If the pOH of a solution is 7.90, determine its hydronium ion concentration. Is this solution acidic or basic?
9. If the hydronium concentration of a solution is 2.40 x 10 -13 mol/L, determine its pOH value. Is this solution acidic or basic?
10. Sulfuric acid has a concentration of 6.00 mol/L, determine its hydroxide concentration.
11. A solution has a pH of 2.76, determine its hydroxide concentration.
12. If the pH of a solution changes by 4 units as a result of adding a strong base, by how much does the hydronium ion concentration change? Does it increase or decrease?
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