c3.1

Question 1

law of conservation of mass

Answer 1

no atoms are lost or made during a chemical reaction

Question 2

in a chemical reaction, is there any change in overall mass of substances

Answer 2

no, overall mass of products will be exactly the same as the overall mass of reactants

Question 3

3 reasons why total mass may appear to change during chemical reaction

Answer 3

(first two best to give in exam)
- gases from air may react with the chemicals in the beaker, increasing the mass
- gaseous products may escape from the beaker into the air, decreasing the mass
- some chemicals may be lost via spilling or evaporation, decreasing the mass

Question 4

ammonium

Answer 4

NH₄⁺

Question 5

hydroxide

Answer 5

OH¯

Question 6

nitrate

Answer 6

NO₃⁻

Question 7

carbonate

Answer 7

CO₃²⁻

Question 8

sulfate

Answer 8

SO₄²⁻

Question 9

you can investigate conservation of mass by

Answer 9

carrying reaction out in closed system
eg:
- a beaker of reactants in solution where the products are not gases
- a flask

Question 10

half equations

Answer 10

losing -> left ( as in larger part)
gaining -> right

Question 11

ionic equations

Answer 11

split aqueous compounds
cross out spectator ions
rewrite

Question 12

mole

Answer 12

m
n mr

Question 13

conc

Answer 13

n
c (mol dm-3) v (dm3)

Question 14

avogadros constant

Answer 14

6.023 x 10^23

Question 15

avogadros constant fomula

Answer 15

particles
n L
L = avogadros constant