C5

Question 1

what is a substances molar mass

Answer 1

1 mole of that substance

Question 2

how many atoms in a mole

Answer 2

6.02x10^23

Question 3

metal carbonates will thermally decompose into…

lead carbonate

Answer 3

metal oxide + carbon dioxide

lead oxide + carbon dioxide

Question 4

what is Ar

Answer 4

relative atomic mass (elements)

e.g. H=1, O=16, K=39

Question 5

What is Mr

Answer 5

relative formula mass (compounds)

e.g. H2O=18, O2=32, H2=2

Question 6

how much PbO (lead oxide) is made when 267g of PbCO3 is heated
Pb=207
O=16
C=12

Answer 6

LOOK AT PAGE 40 i think it gets more complicated then that

Question 7

number of moles X molar mass=

Answer 7

mass of chemical

Question 8

number of moles of H2 in 6g of hydrogen

number of moles X molar mass= mass of chemical

Answer 8

molar mass = Mr (H2) = 2
mass of element/molar mass
6/2 = 3 moles

Question 9

calculate the mass of 0.5 moles of MgO
Mg=24
O=16

Answer 9

number of moles X molar mass= mass of chemical
0.5 X (24+ 16)g/mol = 20
= 20g

Question 10

what is empirical formula

Answer 10

dividing a compound into a ratio

Question 11

empirical formula for
C6H12O6
HCOOH (CH2O2)
C2H4O2

Answer 11

CH2O
CH2O2
CH2O

Question 12

calculate empirical formula form actual mass

Answer 12

write down the mass of each element 
H=0.05g S=0.8g O=1.6g
look up the atomic mass of each element
H=1 S=32 O=16
work out how many moles there are 
0.05/1 = 0.05 mol, 0.8/32=0.025 mol, 1.6/16=0.1 mol .
choose the element present in the smallest amount and divide by it 
0.05/0.025=2
0.025/0.025=1
0.1/0.025=4
H2SO4

Question 13

find the percentage carbon in C2H6

Answer 13

C=12 H=1

(12x2)x100/30 =80%

Question 14

how many liters in 1dm3

Answer 14

1

Question 15

what is the value used in concentration

Answer 15

mol/dm3

Question 16

if a solution is diluted 3 times it will

Answer 16

take up 3 times more volume

Question 17

concentration X volume

Answer 17

amount of moles