2.1.3 Amount of Substance Flashcards
Definition of amount of substance
Number of particles in a substance (measured in moles)
Definition of mole
A unit of measurement containing 6.022 x 10^23 particles
Definition of molar mass and units
mass per mole g mol-1
Definition of molar gas volume
gas volume per mole dm3 mol-1
Definition of empirical formula
Simplest whole number ratio of atoms of each element in a compound
Definition of molecular formula
number and type of atoms of each element in a molecule
Definition of water of crystallisation
The water that is part of the crystalline structure (water that is locked in between the ions of an ionic lattice)
Definition of anydrous
Substance that contains no water of crystallisation
Definition of hydrated
Substance that contains water of crystallisation
% by mass of N In NH4NO3
35.0%
Equation for percentage atom economy
Percentage Atom Economy=((Mr of desired product)/(Total Mr of all products))×100
% by mass of O in CuSO4.5H2O
57.7
Bromomethane is reacted with sodium hydroxide to make methanol.
CH3Br + NaOH → CH3OH + NaBr
Calculate the percentage atom economy for this reaction.
23.7%
How many atoms are in two moles of atoms
1.2 x 10^24
How many electrons are in one mole of sodium atoms?
6.62x10^24
In the ionisation of 2 moles of Ne, how many electrons are released?
1.2 x 10^24
How many protons are there in 3 moles of nitrogen gas?
2.5 x 10^25
how many moles of CO2 are there 11 g of carbon dioxide? How many moles of C atoms? How many moles of O atoms?
n(CO2) = 0.25 n(C) = 0.25 n(2) = 0.50
What mass of magnesium oxide is formed by the complete combustion of 12 g of magnesium?
20 g
8) What mass of potassium oxide is formed when 7.8 mg of potassium is burned in oxygen?
9.4 x 10^-3 g (9.4 mg)
In the manufacture of titanium, what is the limiting reagent and what mass of titanium can theoretically be formed when 1 kg of titanium chloride reacts with 0.1 kg of magnesium?
98.6 g
Mg is the limiting reagent.
Equation for percentage yield
actual yield/theoretical yield x100
2.3g of sodium reacts with an excess of chlorine to produce 4.0g of sodium chloride. What is the percentage yield?
68%
40.0 g of Fe2O3 was found to produce 16g of iron metal. Calculate the percentage yield and the atom economy.
PY=57% AE=52%
A compound contains 50% of sulphur combined with 50% of oxygen. Calculate the empirical formula.
SO2
50.0 g of a compound contains 22.4 g of potassium, 9.2 g of sulphur, and the rest oxygen. Calculate the empirical formula of the compound.
K2SO4
3.53 g of iron reacts with chlorine to form 10.24 g of iron chloride. Find the empirical formula of the iron chloride.
FeCl3
- An oxide of phosphorous contains 56.4% phosphorous and 43.6% oxygen. Its Mr is 220. Find both the empirical and the molecular formula of the oxide.
EF= P2O3 MF= P4O6
- A compound contains 40.0 % of carbon 6.7 % of hydrogen and oxygen. It has a relative molecular mass of 60. Determine both the empirical and molecular formula of the molecule.
EF= CH2O MF= C2H4O2
10.00 g of hydrated barium chloride is heated until all the water is driven off. The mass of anhydous compound is 8.53 g. Determine the value of x in BaCl2.xH2O
x=2
5) Nickel combines with carbon monoxide to form nickel carbonyl, Ni(CO)x .When 2.95 g of Ni was warmed gently in carbon monoxide it was converted completely into 8.55 g of nickel carbonyl. Find the mass of carbon monoxide which has combined with the 2.95 g of Ni and then deduce the value of x in the formula
x=4
What is the ideal gas equation
PV=nRT
What units should each term of the ideal gas equation be in
P = Pa V = m3 T = K
Covert each of the following to m3:
20 000 cm3
0.15 cm3
2.8 dm3
- 02
- 5x10^7
- 8 x 10^-3
Convert each of the following to Pa:
1 atm
0.02 atm
0.3 kPa
101000
2020
300
Convert each of the following to K:
180 oC
-40 oC
453 K
233 K
A gas sample whose relative molecular mass is 153, occupies 1550 cm3 at room temp and pressure. What is the mass of the gas sample
n=0.064 mol, mass = 9.83 g
0.800g of a gas was placed into a vessel of volume 0.950 dm3 at a temperature of 298K. The gas was found to exert a pressure of 0.550 atmospheres. Calculate the relative molecular mass of the gas
n = 0.021 mol, Mr = 37.6 g mol-1
What volume of gas is produced when 82.75g of lead (II) nitrate is thermally decomposed at 101 kPa and 100 o C.
n(Pb(NO3)2 = 0.25, n(gas products) = 0.62 mol, V=0.0192 m3
Nitromethane, CH3NO2, burns in oxygen forming three gases.
2CH3NO2(l) + 1½ O2(g) –> 2CO2(g) + 3H2O(g) + N2(g)
A 100g sample of nitromethane was completely burned in oxygen. Calculate the total volume of gaseous products at 400K and 100kPa.
n(CH3NO2) = 1.64, n(gas products) = 4.92 mol, V= 0.16 m3
What mass of potassium chlorate (V) must be heated to give 1.00 dm3 of oxygen at 20.0ºC and 100 kPa. 2 KClO3(s) → 2 KCl(s) + 3 O2(g)
n(O2) = 0.041 mol, 2735g
