quantative chemistry (paper 1)

Question 1

what are reactants

Answer 1

going in the reaction on the left arrow

Question 2

what are products

Answer 2

come out on the right of the arrow

Question 3

what is the law of conservation of mass

Answer 3

No atoms are lost or made during a chemical reaction so the mass of the products equals the mass of the reactants

Question 4

rules of balancing equations

Answer 4

u cannot change subscript answers, e.g CO2 H2O CH4

you can add numbers in front to change ratio of compounds e.g 2H2O or 3CH4

Question 5

what is 1 mole equal to

Answer 5

6.02x10 (23)

Question 6

triangle for moles mass and molar mass calculations

Answer 6

mass

mole molar mass

Question 7

why did the heated piece of magnesium in the chemical reaction mass increase

Answer 7

mass of magnesium increased when heated up because magnesium reacts with oxygen to form magnesium oxide. magnesium gives two electrons to oxygen to form the white powder, therefore the mass increase because of the oxygen

Question 8

how does lithium carbonate react in chemical reaction

Answer 8

Lithium carbonate is a gas and the crucible lid is loose therefore gassed can go in and out as carbon dioxide is a gas it can escape so the mass decreases. this is an example of thermal decomposition

Question 9

what is the mass number of element symbol

Answer 9

AR

Question 10

what is the mass number of compounds symbol

Answer 10

MR

Question 11

how many cm3 in 1dm3

Answer 11

1000cm3

Question 12

what is a standard solution

Answer 12

A solution of accurately known concentration

Question 13

how do u work out concentration

Answer 13

conc (g/dm3) = amount of solute (g)
—————————-
vol of solution (dm3)

if working in cm3 use:

conc (g/dm3)= amount of solute (g)
—————————- x1000
vol of solution (cm3)

Question 14

how do mass of solute and volume of water affect concentration of solution

Answer 14

the mass of a solute and volume of water affect the concentration of a solution as the greater the mass of solute the smaller the concentration, and greater the volume of water the smaller the concentration and vise versa

Question 15

example of concentration of solute
when: 50g sodium hydroxide
200cn3 of solution

what is concentration in g/dm3

Answer 15

1dm3= 1000cm3

50g
—— = 0.25 0.25/cm3 x1000 = 250g/dm3
200cm3

Question 16

calculating mass of solute example

sodium chloride conc = 200g/dm3
mass = 700cm3

Answer 16

700
——- =0.7dm3
10000

make solute the subject:
amount of solute= conc X volume of solution

so

200gX0.7 = 140g

Question 17

what is a mole

Answer 17

relative atomic mass in grams or relative formums mass in grams

Question 18

how to calculate miles from masses

Answer 18

mass (g) mass (g)
————- or —————-
AR MR

Question 19

how to calculate masses from moles

Answer 19

mass (g)= number of moles X AR

or

mass (g)= number of moles X MR

Question 20

24g of magnesium reacted with 71g of chlorine. calculate the mass of magnesium chloride produced

magnesium + chloride = magnesium chloride
mg + Cl2 =MgCl2

Answer 20

24g reacts with 71g
so 24+71 =95
so MgCl2= 95g because the reactants must equal the products

Question 21

how are ionic compounds formed

Answer 21

when metals react with non metals

Question 22

what ions does metals and non -metals from

Answer 22

metals form positive ions

non metals form negative ions

Question 23

how do the charges of ions relate to periodic table

Answer 23

na is + ion (group 1)

mg 2+ (group 2)
al 3+ (group 3)

Question 24

key rule for formal of an ionic compound

Answer 24

in an ionic compound the charges on the ions have to cancel out to leave an overall charge of zero

Question 25

how to work out the formula of an ionic compound

with sodium chloride

Na+ and Cl-

Answer 25

the single negative charge and the single positive charge can cancel out charge.

Na+ Cl-
multiply both by 1 and get NaCl