Chemistry Answers

5.0 mole of ammonia were introduced into a 5.0 L reaction chamber in which it is partially decomposed at high temperature. At equilibrium at a particular temperature,80% of the ammonia had reacted. calculate Kc?

Calculate temporary and total hardness of water sample of water 

containing: Mg(HCO3)2=9.3 mg/l, Ca(HCO3)2=17.4 mg/l, MgCl2=8.7 mg/l and 

CaSO4= 12.6 mg/l.

Butanoic acid (C₃H₇COOH) is described as a weak acid. Define the term weak acid.

a farm worker is exposed to trifluralin, a commonly used pesticides while working in the fields. Calculate the risk of the worker exposed to 0.01mg/m³ who works 8 hours per day, 7 weeks, for 4 months a year, and for 25 years. Assume a body weight of 70kg and an inhalation volume of 20m³ per 8 hours. The slope factor for Trifluralin is 8.4*10^-1 (mh/kg.day)^-1

Describe how to prepare 250 cm3 of sodium carbonate solution at a concentration of 0.5 mol dm-3 supplied Na2CO3, 10HO crystals.

The equilibrium constant for the production of ammonia, used as fertilizer, is 3.65x 10

8 at 25 ⁰C. N2(g) + 3 H2(g) ⇋ 2 NH3(g) . Calculate the equilibrium concentration of hydrogen gas, if at

equilibrium the concentrations of nitrogen and ammonia are 2.56 M and 5.76 M

State six reasons why measurements are done in chemistry and how a measure is stated

1. What is the difference between tap water and distilled water?

2. Which is effective in removing oily stains in tap water and distilled water? Is it soap or detergent?

3. How does the hardness of water affect the cleaning performance of soap and detergent?

4.How do builders help in the cleaning process?

2. 10.0 g of steam at 120.0 °C are converted into ice at -20.0°C.

a) Make a graph to indicate this change.

b) Calculate the total energy released (J) needed to do the problem above.

1. A sample of water with a mass of 23.0 grams at a temperature of -46.0°C increases to 40°C.

a) Make a phase change diagram to indicate the changes water will undergo in this problem & label each step.

b) How much total heat (Joules) is needed to do the problem above?