Quantitative Chemistry

Question 1

what is the formula of percentage mass of an element in a compound?

Answer 1

atomic mass x number of atoms of that element / RFM of compound

Question 2

what is avogadros constant?

Answer 2

6.02 x 10 ^23

Question 3

what is the equation for moles?

Answer 3

moles = mass / RFM

Question 4

what happened to atoms in a chemical reaction?

Answer 4

they are conserved

NO ATOMS are destroyed or creates

Question 5

usually how is mass lost in a chemical reaction?

Answer 5

GAS

Question 6

what determines the amount of product formed?

Answer 6

the LIMITING REAGENT

Question 7

what does one mole of any gas occupy?

Answer 7

24 dm^3 AT 20 degrees

Question 8

what is the equation for volume of gas?

Answer 8

(mass of gas / RFM of gas ) x 24

Question 9

what is the equation for concentration?

Answer 9

concentration ( mol/dm^3) = moles / volume(dm^3)

Question 10

what is the concentration?

Answer 10

the amount of substance in a certain volume of a solution

Question 11

what is the equation for atom economy?

Answer 11

(RFM of desired product / RFM of all reactants) x 100

Question 12

what does a 100% atom economy mean?

Answer 12

ALL the atoms in the reactants have turned into the desired product - more “green”

Question 13

what does a low atom economy mean?

Answer 13

• more waste products which is bad for the environment
• unsustainable
• use up resources quickly
• not as profitable

Question 14

what does percentage yield do?

Answer 14

compare actual and theoretical yield

Question 15

what is the equation for percentage yield ?

Answer 15

( mass of product actually made / maximum theoretical mass of product) x 100

actual / theoretical

percentage - LESS THAT 100

Question 16

what is yield like fir reversible reactions?

Answer 16

it will never be 100% as the products can turn back into reactants