Methods/calculation/formulas

Question 1

What is the formula for Mr
Example of HNO3
H-1
N-14
O-16

Answer 1

Sum of all of the relative atomic masses (Ar)
E.g.-
1(H) + 14(N) + (3x16(O)) = 63

Question 2

What is the Ar

Answer 2

Relative atomic mass- BOTTOM NUMBER

Question 3

Balance

Cu + O2 — CuO

Answer 3

2Cu + O2 — 2CuO

Question 4

How to balance combustion reactions (tip)

Answer 4

Balance in order!

Question 5

balance this combustion reaction

CH4 + O2 — CO2 + H2O

Answer 5

in order!!!
Carbon
Hydrogen
Oxygen

CH4 + 2O2 — CO2 + 2H2O

Question 6

Calculating mass of product

Answer 6

1- find out if your being asked to find the mass of product or reactant;
Reactant - mr reactant / mr product
Product- mr product / mr reactant

Then x by known mass

Question 7

What is the mass number

Answer 7

TOP NUMBER

protons + neutrons

Question 8

What is the atomic number

Answer 8

BOTTOM NUMBER

Number of protons

Question 9

What is an isotope

Answer 9

Same number for protons but different number of neutrons

Question 10

Formula for average atomic mass

Answer 10

(% of isotope 1 x mass no) + (% of isotope 2 x mass no)

/ 100

Question 11

How to calculate concentrations of solutions in g dm3

FORMULA TRIANGLE

Answer 11

Mass(solute in g)

Concentration Volume(of solution dm3)

Question 12

Converting dm3 to cm3

Answer 12

Cm3-dm3 (/1000)

Dm3-cm3 (x1000)

Question 13

Number of moles in a substance (formula triangle)

Answer 13

Mass

Ar or Mr Moles

Question 14

Formula triangle for number of particles In a substance

Answer 14

Particles

Moles Avogadro constant number

Question 15

Empirical formula step by step

Answer 15

Write down mass of each element
Mass of each element \ atomic mass
Ratio
Formula

Question 16

How to calculate Rf value

Answer 16

Distance traveled by dye-spot
/
Distance travelled by solvent (liquid)