Amount Of Substance Flashcards
What is molar mass and what is it’s units?
The mass of one mole of something
G mol ^-1
What is the value of a mole and what is this value called?
6x10^23
Avogadro’s constant
Calculate the molar mass of Ni(OH)2
Mr = 58.7 + (2x(16+1)) = 92.7
92.7 g mol^-1
How do you calculate moles, when conc is not given?
Moles = mass of a substance / molar mass
Calculate the moles of CaBr2 in 39.98g
0.2 moles
A compound has 0.05 moles and weighs 2.6 g. Find it’s relative molecular mass
52
What is the equation of moles when concentration is given?
Moles = conc x volume / 1000
When in cm^3
A 0.5 mol dm^-3 solution of ZnSO4 contains 0.08 moles what volume does this occupy?
0.16 dm^3
What mass of sodium hydroxide needs to be dissolved in 50cm3 of water to make a 2M solution?
4g
What is the equation to work out the mass of a gas (in standard conditions) when only volume is given?
Moles = volume / 24 (in dm^3) Moles = volume / 24000 (in cm^3)
What volume in cm^3 does 0.02 moles of hydrogen gas occupy in standard conditions?
= 0.02 x 24000 = 480 cm ^3
What is the ideal gas equation?
PV = nRT
At a temperature of 60oC and a pressure of 250KPa a gas occupied a volume of 1100 cm3 and had a mass of 1.6g.
Find it’s relative molecular mass
16
Balance the equation
C2H6 + O2 —> CO2 + H2O
C2H6 + 3.5O2 —-> 2CO2 + 3H2O
Calculate the mass of iron oxide produced if 28g of iron is burnt in air in this equation:
2Fe + 1.5 O2 —-> Fe2O3
40g of iron oxide
What are the state symbols?
G , l, S, aq (solution in water)
What do you produce when an acid reacts with a an alkali?
A Salt and water
What can we use titration so to find out?
How much acid is needed to neutralise a quantity of alkali
Calculate volumes
Calculate concentrations
25cm3 of 0.5M HCL was used to neutralise 35cm3 of NaOH solution. Calculate the concentration of sodium hydroxide and give units
0.36 mol dm^-3
20.4 cm3 of a 0.5 M solution of Na2CO3 reacts with 1.5 M nitric acid. Calculate the volume of nitric acid needed to neutralise this.
Na2CO3 + 2HNO3 —-> 2NaNo3 + H2O + CO2
13.6 cm^3
What is empirical formula?
The simplest ratio of different atoms in a compound
How do we calculate percentage yield?
Percentage yield = actual yield / theoretical yield x 100
How do we calculate atom economy?
Atom economy = mass of desired product / total mass of reactants x 100
