Unit 1 - Calculations T3

Question 1

GFM calculations

Answer 1

Find RAM of each element in data book, if there are multiple of those elements in compound times it’s value by how many there are. Add values for each element together. Easy game.

Question 2

Mass calculations - equation

Answer 2

Triangle with m measured in grams at top.
n - moles and GFM below.
m = n x GFM
n = m over GFM
GFM = m over n (never usually asked to figure out)

Question 3

Mass calculations - exam answering exam q.

Answer 3

1. Write out equations
2. Find what info you’re given and what you need to find. Can scribble out all that is unnecessary. Draw line between molecules asked about.
3. For molecule that info has been given - find GFM and state info already given - most likely not moles. May have to convert mass into g
4. Using mass triangle find unknown - usually moles.
5. Do a mole to mole ratio, if there is no. before compound take into consideration while doing ratio. I.e 1:2 or 5:3
   Use this to find moles on each side I.e 0.16:0:32.
6. Now that moles are known find most likely GFM of substance and put into mass equation, and work usually mass.
7. Write answer and remember units.

Question 4

Concentration calculation - equation.

Answer 4

n (number of moles) top of triangle
c (concentration) in moll-1 and v (volume) in litres.
c = n over v
n = c x v
v = n over c

Question 5

concentration calculation - answering in exams.

Answer 5

1. Write out equations
2. Find what info you’re given and what you need to find. Can scribble out all that is unnecessary. Draw line between molecules asked about.
3. For molecule info has been given info about state info and work out moles using concentration equation. May have to convert to litres.
4. Do a mole to mole ratio, if there is no. before compound take into consideration while doing ratio. I.e 1:2 or 5:3
   Use this to find moles on each side I.e 0.16:0:32.
5. Now that moles are known work out either volume or concentration using concentration equation. You will be given one of values - may have to convert units again.
6. State ans with appropriate units.

Question 6

Mass and concentration calculations - answer in exams

Answer 6

Do same thing for others except use appropriate equations for each.