Homework Answers

Solve and show step by step solution.

1. The density of the solution is 0.982 g/mL and the density of water is 1.00

g/ml. If the solution is composed of 30.6 g NH3 in 81.3 g of H2O. Compute for;

a. mole fraction of NH3

b. molarity of NH3

c. molality of NH3

2. Given the reaction, H3PO4 + 3 NaOH Na3PO4 + 3 H2O, what is the

mass of 0.20 M H3PO4 needed to react with 100 ml. of 0.10 M NaOH?

1. Why does the Department of Health (DOH) recommends the use of 70% rubbing alcohol than 40% as a precautionary measure against corona virus?

2. Why does the Department of Environment and Natural Resources, (DENR) concern on the cauliform level, in parts per million, during the rehabilitation of beaches in Boracay? Research on the tolerable level of cauliform.

1. What is the percent by mass concentration of 41.0 g of sodium chloride

(NaCl) dissolved in 331 g of water (H2O)?

2. What is the percent by volume concentration of 25 ml ethanol (C2H5OH) in

75 ml solution?

3. What is the mass in grams of potassium nitrate (KNO3) needed to prepare

650 ml of 3.2 M KNO3 solution?

4. What is the molal concentration of a solution that contains 16 g of silver

nitrate (AgNO3) in 80 ml of water.

5. What is the molarity of 15.2 % by mass hydrogen peroxide (H2O2)? The

density of the solution is 1.01 g/ml.

Complete the balanced chemical equation for the reaction of CaCO3 and HCl

producing CaCl2, H2O and CO2. Fill in the concept map if we need to find the volume

of HCl given its molarity and mass of CaCO3.

Balanced Chemical Equation:

___ CaCO3 + ___ HCl ___ CaCl2 + ___ H20 + ___ CO2

Concept Map:

Mass of CaCO3,__________,___________,Volume of HCl

A 100 mL concentrated sulfuric acid (normally an Analytical Reagent, AR) will be weighed exactly to be used in a back-titration analysis. Explain how you will do this in the laboratory.