Topic 3-Quantitative chemistry (2) from january

Question 1

What do titrations (experiments) let you find?

Answer 1

the volumes needed for two solutions to react together completely

Question 2

When one solution’s concentration is known, how could you find the concentration of the second solution?

Answer 2

you can use volumes from the titration experiment along with the reaction equation

Question 3

GASES AND SOLUTIONS:
What volume does one mole of any gas occupy at 20 degrees?

Answer 3

24 dm cubed

Question 4

GASES AND SOLUTIONS:
What conditions are needed for one mole of a gas to occupy 24 dm cubed?

Answer 4

room temperature and pressure
(r.t.p. = 20 degrees and 1 atm)

Question 5

GASES AND SOLUTIONS:
What is the concentration of a substance?

Answer 5

The amount of a substance (e.g. the mass or number or moles) in a certain volume of a solution

Question 6

GASES AND SOLUTIONS:
What is the solute?

Answer 6

the substance that’s dissolved

Question 7

GASES AND SOLUTIONS:
What is the solvent?

Answer 7

The solution that the solute is dissolved in

Question 8

GASES AND SOLUTIONS:
The more solute there is in a given volume…

Answer 8

the more concentrated the solution

Question 9

GASES AND SOLUTIONS:
Give one way to calculate the concentration of a solution?
What would the units of this be?

Answer 9

calculate the mass of a substance in a given volume of solution
units = units of mass/units of volume

Question 10

GASES AND SOLUTIONS:
REMEMBER:
At the same temperature and pressure, equal numbers of moles of any gas will occupy the same volume.

Answer 10

;)

Question 11

LIMITING REACTANTS:
What happens when one reactant gets completely used up in a reaction before the rest?

Answer 11

the reaction will stop

Question 12

LIMITING REACTANTS:
When will a reaction stop?

Answer 12

When one reactant is used up (this is the limiting reatant)

Question 13

LIMITING REACTANTS:
When some magnesium carbonate is placed into a beaker of hydrochloric acid, how can you tell that a reaction is taking place?

Answer 13

lots of gas bubbles will be given off (effervescence)

Question 14

LIMITING REACTANTS:
What happens to the reactants that aren’t all used up?

Answer 14

they are in excess

Question 15

LIMITING REACTANTS:
Why may some reactants be added in excess?

Answer 15

to make sure that the other eactant is used up

Question 16

LIMITING REACTANTS:
What is the reactant that is used up called?

Answer 16

the limting reactant (because it limits the amount of product that is formed)

Question 17

LIMITING REACTANTS:
What is the relationship between the amount of product formed and the amount of limiting reactant?

Answer 17

They are directly proportional

Question 18

LIMITING REACTANTS:
If you halve the amount of limiting reactant, what happens to the amount of product formed?

Answer 18

it will also halve

Question 19

LIMITING REACTANTS:
If you double the amount of limiting reactant, what happens to the amount of product formed?

Answer 19

the amount of product will double (as long as it is still the limiting reactant)

Question 20

LIMITING REACTANTS:
Explain why adding more limiting ractant will increase the product formed by the same amount?

Answer 20

• adding more reactant means there are more reactant particles to take part in the reaction
• this means more product particles can be formed

Question 21

LIMITING REACTANTS:
What does the amount of product formed depend on?

Answer 21

the amount of limiting reactant

Question 22

LIMITING REACTANTS:
What is the mass of product called?
What are the masses you calculate called? Why?

Answer 22

• mass of product - yield of reaction
• theoretical yields (on practice you never get 100% of the yield, so the amount of product you get will be less than you calculated)