Question

Answer the questions completely with complete calculations.

1. Balance the following equation & fill in the state of the chemicals.

a. Fe2 (SO4)3 (aq) + NH3 (aq) + H2O (l) --> Fe (OH)3 ( ) + (NH4)2SO4 ( )

2. How many atoms of oxygen are present in 1.75 g sample of Fe2 (SO4)3?

3. Calculate the percentage of Cl by mass in PCl5

4. Predict whether each of the following ionic compounds is likely to be water soluble.

KCl _____; MgCO3 ____

Fe2O3 ____; Cu(NO3)2 _____

In which compound will the bulb be lit most brightly? why?

5. What is the oxidation number of element in BrO2-, BrO3- & BrO4-, Br2, Br-?

6. In the reaction 4 NH3 (g) + 5 O2 (g) --> 4 NO (g) + 6 H2O (l)

750 g NH3 is mixed with 750 g of O2.

a. what is the amount of NO produced in this reaction?

b. which is the limiting reagent?

c. How much of the excess reagent remains?

d. The actual yield of NO obtained was 400g. What is the % yield of NO?

7. A compound of 49.4% K, 20.3% S, and 30.3% O by mass. What is empirical formula of the compound?

8. How many grams of a sample of NaNO3 should be dissolved in a 150.0 mL of water to give a 0.22 M solution?

9. A certain alcohol contains only three elements C, H & O. Combustion of 50.00 g sample of the alcohol produced 95.50 g of CO2 and 58.70 g of H2O. What is the empirical formula of the alcohol?

  

Answer 1

a. Fe2 (SO4)3 (aq) + 6NH3 (aq) +6 H2O (l) --> 2Fe (OH)3 ( s ) + 3(NH4)2SO4 (aq )

2. How many atoms of oxygen are present in 1.75 g sample of Fe2 (SO4)3?

mol = mass/MW = 1.75/399.88 =

0.0043763 mol of Fe2(SO4)3; we want Oxygen so 1 mol of Fe2(SO4)3 contains 12 mol of O

then

0.0043763*12 = 0.0525156 mol of Oxygen

1 mol = 6.022*10^23 then

0.0525156*6.022*10^23 = 3.16248*10^22 molecules of Oxygen

3. Calculate the percentage of Cl by mass in PCl5

%Cl = mass of Cl / total mass * 100 = 35.5/208.24 *100 = 17.047%

4. Predict whether each of the following ionic compounds is likely to be water soluble.

KCl __soluble, since K+ is alkali___; MgCO3 not soluble, since CO3-2 of Mg arenot soluble

Fe2O3 insoluble; Cu(NO3)2 soluble

In which compound will the bulb be lit most brightly? why? KCl, since it is pretty ionic, K+ and Cl- will be used as electrolyte

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