Moles
What is the mass of 0.25 moles of aluminium oxide (Al2O3)?
25g
Determine the EF of the compound with 2.74% hydrogen and 97.26% chlorine.
HCl
Determine the molecular formula of the compound HO (EF) with a relative molecular mass of 34.
H2O2
Explain how percentage of yield is calculated.
(actual yield/theoretical yield) x 100
Explain the term 'endothermic' in relation to the total amount of chemical energy of the reactants and products.
How many moles of oxygen atoms are in 2.5 mol of H2SO4 molecules?
10
Calculate the percentage by mass of iron in iron (III) oxide (Fe2O3).
69.94%
Determine the molecular formula of CH2O (EF) with a relative molecular mass of 90.
C3H6O3
Define limiting reagent
The reactant that is totally consumed when the chemical reaction reaches completion.
When methane (CH4) combusts, it reacts with oxygen to form carbon dioxide and water. The heat of combustion of methane is -890kJ/mol. Represent this reaction with a thermochemical equation.
CH4 (g) + 2O2 (g) -> CO2 (g) + 2H2O (l) delta H= -890 kJ/mol
How many molecules are there in 4.28mg of aspartamine (C14H18N2O5)?
8.76 x 10^18
What is the EF for the compound with the following percentages by mass: Fe 20.09%, S 11.55%, H 5.04%, O 63.32%?
FeSO11H14
Determine the molecular formula of NO2 (EF) with a relative molecular mass of 46.
NO2.
Sodium metal reacts with chlorine gas to form sodium chloride. 25g of sodium reacted with 50g of chlorine gas. Calculate the mass of sodium that will form in the reaction.
63.7g
(Table 10.2.1)- Predict the enthalpy change of 2Hf (g) -> H2 (g) + F2 (g).
+543
Calculate the total number of atoms in 288g of ammonia (NH3).
4.08 x 10^25 atoms
Nicotine was found to have the following percentages by mass: 74.0% C, 8.7% H and 17.3% N. Its relative molar mass was found to be 162. State the EF.
C5H7N
Which is both an empirical and molecular formula: H2O2 or C12H22O11?
C12H22O11
The combustion of ethanol yields carbon dioxide and water (C2H5OH + 3O2 -> 2CO2 + 3H2O). Which reactant is in excess and which is limiting?
Excess= Air (O2)
Limiting = Ethanol
Table 10.2.1- Predict the enthalpy change of C (g) + 2H2 (g) -> CH4 (g)
-780
If the body of a person is 80% water, how many moles of water would be in the body of a person who weighs 80kg?
3552 moles
In an experiment to find the formula of a compound, copper (II) oxide was heated until only pure metallic cooper remained. The following results were obtained:
mass of crucible = 35.030g, mass of crucible + copper = 38.205g, mass of crucible + copper (II) oxide = 39.005g.
Find the EF.
CuO
A hydrocarbon contains 85.7% carbon by mass. Its relative molecular mass is 70. Determine the molecular formula.
C5H10
If 50kg of ZnS yielded 29.5kg of pure zinc (Zn), what is the experimental yield for the process?
88%
Table 10.2.1- Predict the enthalpy change of 2H2 (g) + O2 (g) -> 2H2O (g)
-484