Formative Quiz 1

1.	Predict whether each of the following chemical systems will be acidic, basic, or neutral. Explain your reasoning. Give the appropriate equations to explain your reasoning.
i. aqueous hydrogen bromide
ii. aqueous ammonia
iii. carbonated beverages
iv. limewater (CaCO3)

2.	Given the following experimental evidence, determine the relative strength of the acids in the table below. (The symbols for the indicators in the table correspond to those in Appendix C8). All acid solutions were of equal molar concentration.

	HMv	H2Tb	Hor	HBp	HCr	HCh	
Hydrofluoric, HF (aq)	blue	orange	Orange	violet	blue	yellow	
Acetic, HC2H3O2 (aq)	blue	yellow	Yellow	purple	blue	yellow	
Nitric, HNO3 (aq)	green	red	Red	violet	blue	yellow	
Hydrocyanic, HCN (aq)	blue	yellow	Yellow	red	yellow	yellow	
Methanoic, HCHO2 (aq)	blue	orange	Orange	purple	blue	yellow	
Hydrochloric, HCl (aq)	green	red	Red	violet	blue	yellow	

3.	In the space below, sketch the titration curve (pH vs volume titrant added) when there is hydrazine, N2H4 in the Erlenmeyer flask and HCl in the burett. For this example we will assume that hydrazine can react with two protons. If the equivalency points occur at a pH of 8.75 and 5.7, pick appropriate indicators. 

4.	(a) Write an equilibrium reaction for each of the following buffer mixtures:
i. NH3  (aq) and NH4Cl  (aq)  
ii. HC7H5O2  (aq)  and Na C7H5O2  (aq)  
(b) in what direction would each equilibrium shift ig a small amount of HCl (aq) is added to the buffer solution? Write a reaction  equation that illustrates the cause of each shift.

Acid Base Formative

1.	To determine the number of acidic protons on a weak organic acid, a student decides to perform a number of titrations with a 0.410 mol / L NaOH solution. They measure out 2.24 g of the organic acid and dissolve it into the 50.00 mL of distilled water, and require 25.85 mL of the base to reach the endpoint.

a.	Write the balanced chemical equation in the space below, with the generic acid formula of HxA.
b.	Determine the moles of HxA if the molar mass of the acid was determined to be 211.50 g / mol.
c.	Determine the moles of H+.
d.	Determine the generic formula, showing the number of acidic protons.

2.	What would be the pH of the following solutions. Be sure to EXPLAIN your reasoning:

a.	A solution resulting from the titration of phosphoric acid and lithium hydroxide, if the titration is stopped at the equivalency point.

b.	A solution resulting from the mixing of aqueous silver nitrate and carbon dioxide gas.

c.	A solution resulting from the mixing of solid calcium with water.
2.	
Which of the following solutions is a buffered solution? Explain your decision for each solution.
a.	0.10 M HCN and 0.10 M NaCN
b.	0.10 M NaOH and 0.10 M NaCl
c.	0.10 M NH3 and 0.10 M NH4Br
d.	0.10 M NaOH and 0.10 M KOH
e.	0.10 M NH4Cl and 0.90 NH4Br

3.	A buffered system was established by combining 0.10 M acetic acid (CH3COOH) with 0.10 M NaCH3COO. Describe what would happen when you begin adding:
a. HCl
b. NaOH

4.	A student conducts a series of titrations:
I.	NaOH titrated with HCl
II.	NaOH titrated with CH3COOH
III.	NH3 titrated with HCl
IV.	NH3 titrated with CH3COOH
However, they forgot to label the graphs that were printed off from the computer system. Of the graphs below, determine which graph is associated with which titration. Explain your reasoning.

Acid-Base Salt Calculations

1.	Calculate the pH of each of the following solutions.
a.	0.038 g of barium hydroxide in 250. mL of solution;
b.	0.050 g of hydrogen iodide in 750. mL of solution;
c.	0.00055 g of HCl in 1.00 L of solution.

2.	Calculate the pH of 0.12 mol / L solutions of the following salts: 
a.	NaNO2
b.	NaClO
c.	NaCHOO.
3.	*
3.	What is the pH of a 0.52 mol / L solution of 
a.	KClO? 
b.	KF?

4.	Ascorbic acid, C5H7O4COOH, also known as vitamin C, is an essential vitamin for all mammals. Among mammals, only humans, monkeys, and guinea pigs cannot synthesize it in their bodies. Ka for ascorbic acid is 7.9 x 10-5. Calculate [H3O+] and pH in a 0.110 mol / L solution of ascorbic acid.

5.	Some of the following salts are used in detergents and other cleaning materials because they produce basic solutions. Which of the following could not be used for this purpose? Write equations to justify your answers.
a.	Na2CO3
b.	Na2SO4
c.	(NH4)2SO4
d.	Na3PO4

6.	Some plants require acidic soils for healthy growth. Which of the following could be added to the soil around such plants to increase the acidity of the soil? Write equations to justify your answers. 
a.	Fe2(SO4)3
b.	Na2SO4
c.	Al2(SO4)3
d.	FePO4
e.	BaSO4

1(a) 10.95; 1(b) 3.28; 1(c) 4.82
2(a) 8.11; 2(b) 11.23; 2(c) 8.41
3(a) 10.62, 3(b) 8.45
4 [H3O+] = 2.95 x 10-3 mol/L pH = 2.53
5(a) basic; 5(b) slightly basic; 5(c) acidic; 5(d) basic
6(a) acidic; 6(b) basic; 6(c) acidic; 6(d) basic; 6(e) basic