Chemical Calculations

Question 1

What can you find out from balanced equations?(mole related)

Answer 1

The mole ratio of the reactants and products(number in front)

Question 2

What two formulas can calculate moles?
What are the usual units for them?

Answer 2

n=m/gfm
N-number of moles(mol)
Gfm-gram formula mass(g)
M-mass(g)
C=n/v
C-concentration(moll-1)
N-number of moles(mol)
V-volume(l)

Question 3

What can you use to work out the limiting reactant and reactant in excess for a chemical reaction?

Answer 3

The mole ratio form a balanced equation, when you calculate the mole ratio whichever mole value is higher than the original is the reactant in excess

Question 4

What can you do the ensure a costly reactant is converted into a product?

Answer 4

And excess of the less expensive reactant(s) can be used

Question 5

What is the molar volume?
Is it the same or different for all gases at the same temp and pressure?

Answer 5

The volume occupied by one mole of gas at a certain temperature and pressure
The same

Question 6

How can you calculate molar volume?

Answer 6

MV=V/n
Vm-molar volume(litresmol-1)
V-volume of gas(l)
N-number of moles(mol)

Question 7

What can we work out when comparing volumes of gases?

Answer 7

We can work out the volumes of other reactants and products using their moles
(ONLY ON GASEOUS REACTANTS AND PRODUCTS)

Question 8

What is the efficiency with which reactants are converted into t he desired product measured in?

Answer 8

Percentage yield
Atom economy

Question 9

What is the theoretical yield?

Answer 9

The quantity of desired product obtained assuming full conversion of the limiting reagent

Question 10

What is the actual yield?

Answer 10

The quantity of the desired product formed under the prevailing reaction conditions

Question 11

What does the percentage yield provide?

Answer 11

A measure do the degree to which the limiting reagent is converted into the desired product

Question 12

How do you calculate percentage yield?

Answer 12

%yield=(actual yield/theoretical yield)x100

Question 13

Given costs for the reactants, What can percentage yield be used to calculate the cost of?

Answer 13

The cost of reactants required to produce a given mass or product

Question 14

What is atom economy?

Answer 14

It measures the proportion of the total mass of all starting materials converted into the desired product formed under

Question 15

How do you calculate atom economy?

Answer 15

%atom economy=(mass of desired product/total mass of reactants)x100