Topic 2 Chemical Calculations

Question 1

What are reactants in a chemical reaction?

Answer 1

Substances that REACT together

Question 2

What are products in a chemical reaction?

Answer 2

Substances PRODUCED in the reaction

Question 3

What is a word equation?

Answer 3

Gives the names of the substances involved in a reaction

Question 4

What is a balanced equation?

Answer 4

Gives the symbols and formulas of the substances involved in a reaction

Question 5

What is RAM?

Answer 5

Average mass of a large number of atoms of an element

Question 6

What is RMM?

Answer 6

Average mass of a molecule calculated by adding the RAMs of all the atoms in the formula

Question 7

What is the mole (mol)?

Answer 7

Amount of a substance that contains as many particles as there are atoms in 12g of carbon-12

Question 8

What is Avogadro’s constant?

Answer 8

6.022 x 10^23, the number of particles in one mole of a substance

Question 9

What is molar mass?

Answer 9

Mass of one mole of any substance, expressed in g mol^-1

Question 10

What is the molarity of a solution?

Answer 10

Number of moles of substance in 1L of solution, units: mol L^-1

Question 11

What is the formula for calculating concentration in ppm?

Answer 11

mg of solute per liter of solution

Question 12

What happens in an acid-base (neutralization) reaction?

Answer 12

An acid reacts with a metal hydroxide to produce a salt and water

Question 13

Fill in the blank: The balanced equation for calcium and water is _______.

Answer 13

Ca + 2H2O -> Ca(OH)2 + H2

Question 14

True or False: Balanced equations can have different formulas for the same reactant.

Answer 14

False

Question 15

What does 5% (w/w) solution mean?

Answer 15

5.0 g solute is dissolved in 95.0 g solvent

Question 16

What is the molarity of 1 mole of NaCl in 1 litre of water?

Answer 16

1 M

Question 17

What is the mass of 0.5 moles of hydrochloric acid (HCl)?

Answer 17

18.25 g

Question 18

What is the balanced equation for potassium hydroxide and hydrochloric acid?

Answer 18

KOH + HCl -> KCl + H2O

Question 19

How do you calculate the number of moles from a mass?

Answer 19

Moles = mass (g) / molar mass (g/mol)

Question 20

What is the balanced equation for sulphuric acid and potassium hydroxide?

Answer 20

H2SO4 + 2KOH -> K2SO4 + 2H2O

Question 21

What is the concentration of HCl if 48 mL were neutralized by 54 mL of 0.50 M NaOH?

Answer 21

Calculate using stoichiometry from balanced equation

Question 22

What is a 10% (v/v) solution?

Answer 22

10.0 mL of solute is made up to 100 cm^3 with solvent

Question 23

How many moles of SO2 are in 16.0 g?

Answer 23

0.25 moles (molar mass = 64 g/mol)