Unit 3

Question 1

What is the conservation of mass?

Answer 1

in a chemical reaction, atoms are not created or destroyed, just rearranged, so total mass before = total mass after the reaction

Question 2

When a metal forms a metal oxide, why does the mass increase?

Answer 2

atoms from gaseous oxygen have been added

Question 3

When an acid reacts with a metal, why does the mass decrease?

Answer 3

a gas is produced and escapes

Question 4

What is relative formula mass?

Answer 4

the sum of the relative atomic masses of each atom in a substance

Question 5

What are the four state symbols and what do they stand for?

Answer 5

(s) solid
(l) liquid
(g) gas
(aq) aqueous or dissolved in water

Question 6

How can you tell when a symbol equation is balanced?

Answer 6

the number of atoms of each element is the same on both sides

Question 7

What is a unit for concentration?

Answer 7

g/dm3

Question 8

Which formula is used to calculate volume from concentration and mass?

Answer 8

volume (dm3) = mass/concentration (g/dm3)

Question 9

Which formula is used to calculate mass from concentration in g/dm3 and volume?

Answer 9

mass (g) = concentration (g/dm3) × volume (dm3)

Question 10

How can you convert a volume reading in cm3 to dm3?

Answer 10

divide by 1000

Question 11

If the amount of solute in a solution is increased, what happens to its concentration?

Answer 11

increases

Question 12

If the volume of water in a solution is increased, what happens to its concentration?

Answer 12

decreases