Question

Answer the following Qs:

1)The chemical reaction that represents a dehydration reaction is:

a)		Heating hydrated barium chloride
b)		Heating anhydrous barium chloride
c)		Adding water to anhydrous barium chloride
d)		Adding water to hydrated barium chloride

2)Suppose 0.22 L of 0.5 mol/L NaOH solution was titrated with 5 L of HCl using phenolphthalein indicator. Calculate the amount of the base and the acid that were used to reach the neutralization point.

a)		0.55 mol of the base and 0.55 mol of the acid
b)		0.11 mol of the base and 0.55 mol of the acid
c)		0.55 mol of the base and 0.11 mol of the acid
d)		0.11 mol of the base and 0.11 mol of the acid

3)A mixture of a hydrate and sand has a mass of 10.5 g. After heating the mixture, the mass changes to
10 g. The difference between the two masses is 0.5 g. What does this 0.5 g represent?

a)		Mass of mixture
b)		Mass of hydrate
c)		Mass of water
d)		Mass of barium chloride

4)50 L of 2.0 mol/L Hydrochloric acid is titrated with sodium hydroxide to form water and sodium chloride. How many moles of sodium hydroxide are consumed in this reaction?

		a)2 mol
		b)100 mol
		c)25 mol
		d)0.04 mol

5)20 g of sand was mixed with 5 g of a hydrate. Calculate the percentage of the hydrate in this mixture.

a)		4 %
b)		25 %
c)		0.25 %
d)		20 %

Answer 1

Q1. Correct answer is (a.) Heating hydrated barium chloride

Q2. Correct answer is (d.) 0.11 mol of the base and 0.11 mol of the acid

Q3. Correct answer is (c.) Mass of water

Q4. Correct answer is (b.) 100 mol

Q5. Correct answer is (d.) 20 %

Explanation

Q1. dehydration is removal of water from compound. This removal is usually done by heating the hydrated salt

Q2. moles of NaOH = molarity * volume = (0.5 mol/L) * (0.22 L) = 0.11 mol

moles of HCl used = moles of NaOH present = 0.11 mol

Q3. Mass difference is the mass of water which has evaporated from the mixture when the mixture is heated