Quantitative Chemistry

Question 1

True or false
Compounds have a relative formula mass

Answer 1

True. they do have a relative formula mass

Question 2

What is Relative Formula Mass?

Answer 2

The sum of the relative atomic masses of the atoms in a molecule( bottom number)

Question 3

Formula : PERCENTAGE MASS OF AN ELEMENT IN A COMPOUND

Answer 3

(Aᵣ x number of protons) / (Mᵣ of the compound) x 100

Question 4

What is a mole?

Answer 4

amount of a substance

Question 5

What is the formula for moles?

Answer 5

moles=Mass (g)/ Mr

Question 6

What are the 2 explanations if there is a different mass after a chemical reaction?

Answer 6

1. If the mass is higher, one of the reactants is gas found in the air
2. If the mass is lower, one of the products was gas that escaped

Question 7

What is a limiting reactant?

Answer 7

the reactant which runs out first

Question 8

What is the formula for volume of gas?

Answer 8

Volume of gas = (Mass of gas / Mᵣ of gas) x 24

Question 9

What is the formula for concentration?

Answer 9

Concentration = Mass of solute(g)/ Volume of solvent(dm**3)

Question 10

What is the other formula for concentration?

Answer 10

Concentration = Moles of solute / Volume of solvent

Question 11

How do you convert mol/dm³ to g/dm³?

Answer 11

Find the concentration in mol/dm³ then convert the concentration using the equation:
mass = moles x Mr

Question 12

What is atom economy?

Answer 12

The % of reactants that form useful products

Question 13

What is the formula for atom economy?

Answer 13

Mass of desired product/total mass of products x100

Question 14

What is the percentage yield?

Answer 14

The yield of a chemical reaction describes how much product is made

Question 15

What is the formula for percentage yield?

Answer 15

Mass of product made / Maximum theoretical mass of product x 100

Question 16

What is a mole?

Answer 16

amount of a substance

Question 17

What is Avogadro constant?

Answer 17

602 000 000 000 000 000 000 000 or 6.02*10**23

Question 18

What is the symbol for moles?

Answer 18

mol

Question 19

What is the Mr?

Answer 19

relative atomic mass of its formula in grams if the substance is a
compound

Question 20

What is the Ar?

Answer 20

relative atomic mass of its formula in grams if the substance is an
element

Question 21

How do you find the number of moles?

Answer 21

mass of an element or compound(g)/Mr of the element or compound

Question 22

Why are atoms conserved in a chemical reaction?

Answer 22

because no atoms can be made or destroyed

Question 23

If the mass changes what else is involved?

Answer 23

gas is usually involved

Question 24

How can you balance equations?

Answer 24

using reacting masses

Question 25

Why do chemical reactions stop?

Answer 25

when one reactant is used up this is called the limiting factor

Question 26

What does the amount of product depend on?

Answer 26

limiting factor

Question 27

What is the formula for concentration?

Answer 27

concentration=mass of solute(g)/ volume of solvent in

Question 28

What does one mole of gas occupy?

Answer 28

24dm**3 at 20 degrees

Question 29

What does concentration measure?

Answer 29

how crowded things are

Question 30

What do the little number is chemical equations mean?

Answer 30

how many atoms of each element there are in each substance