Moles
The ammonia formed reacts with nitrogen dioxide to form nitrogen and water.
Balance the equation for this reaction.
.....NO2+......NH3 → .....N2+12H2O
6, 8, 7
An insoluble salt is prepared by mixing solutions of silver nitrate and sodium chloride.
Write a chemical equation for the reaction occurring.
(AQA chemical past paper1)
AgNO3 + NaCl → AgCI +NaNO3
The iron in Fe2O3 is reduced by reaction with carbon monoxide. The unbalanced symbol equation is shown:
Complete the equation:
Fe2O3 +__CO → __CO2 + __Fe
(2023 winter)
3,3,2
What is T.Daniel's favorite color?
Blue
135 moles of urea, (NH2)2CO, is stored in the tank of a car.
Calculate the mass of the stored (NH2)2CO (in kg).
135 × 60 = 8100g
and g to kg conversion = 8.1kg
Zinc can be extracted by heating zinc oxide with carbon. The equation for the reaction is
ZnO + C → Zn +CO
Explain which element is acting as a reducing agent in this reaction.
M1 carbon
M2 it removes oxygen from the zinc (oxide) / causes zinc ions to gain electrons / gains oxygen / is oxidized
A student adds excess large pieces of magnesium carbonate, MgCO3, to dilute hydrochloric acid, HCl, and measures the volume of carbon dioxide gas, CO2, given off.
Add the missing state symbols to the chemical equation for the reaction.
MgCO3 .....+2HCl..... → MgCl2(aq)+H2O .....+CO2 .....
MgCO3(s) + 2HCl(aq) → MgCl2(aq) + H2O(l) + CO2(g)
Determine the volume of CO2 gas given off when excess MgCO3 is added to 25.0 cm3 of 0.400mol/ dm3 HCl at room temperature and pressure.
MgCO3 + 2HCl → MgCl2 + H2O + CO2
Use the following steps.
● Calculate the number of moles of HCl in 25.0 cm3 of 0.400mol/ dm3 of acid. .............................. mol
● Determine the number of moles of CO2 gas given off. .............................. mol
● Calculate the volume of CO2 gas given off in cm3 . .............................. cm3
M1 mol HCl = 0.400 × 25.0 / 1000 = 0.01
M2 mol CO2 = M1 / 2 = 0.0100 / 2 = 0.005
M3 volume CO2 = M2 × 24000 = 120 (cm3)
Complete the following equation.
ZnCO3+ H2SO4 → .......+…….+…….
ZnCO3 + H2SO4 → ZnSO4+ CO2 + H2O
correct formula for zinc sulfate = 1
Write the ionic equation for the formation of lead(II) chloride by mixing aqueous solutions.
Include state symbols.
(2023 winter)
Pb2+(aq) + 2Cl-(aq) → PbCl2(s)
which planet is the furthest to us in solar system?
Neptune
Lead(II) sulfate is an insoluble salt. Lead(II) sulfate can be made from aqueous ammonium sulfate using a precipitation reaction.
(i) Name a solution that can be added to aqueous ammonium sulfate to produce a precipitate of lead(II) sulfate. (1)
(ii) Write an ionic equation for this precipitation reaction. Include state symbols. (3)
(June 2023)
lead(II) nitrate
(ii) Pb2+ (aq) +SO42-(aq) → PbSO4(s)
M1 PbSO4 on the right
M2 only Pb2+ and SO42– on the left
M3 (aq) + (aq) → (s)
This question is about the insoluble salt lead(Il) bromide.
(a) A student uses the precipitation method to prepare lead (Il) bromide.The equation for the reaction she uses is
Pb(NO3)(aq) + 2NaBr(aq) > PbBr2(S) + 2NaNO3 (aq)
Describe how she could use solutions of lead(II) nitrate and sodium bromide to obtain a pure, dry sample of lead (II) bromide.
(AQA chemical past paper2)
mix / add / react (the two) solutions / salts together stir filter wash (with water) suitable method of drying
identifying two suitable pieces of apparatus
Tetrachloromethane gas, CCl 4(g), reacts with steam as shown.
CCl 4(g) + 2H2O(g) CO2(g) + 4HCl(g)
The reaction is reversible. The forward reaction is exothermic.
(State what happens, if anything, to the rate of the forward reaction if the concentration of CCl4 is increased.
Explain your answer in terms of collision theory.
(2023 winter)
M1 rate of reaction increases
M2 more (CCl4) particles per unit volume
M3 frequency of collisions between (CCl4 and H2O) particles increases
Many organic compounds contain carbon, hydrogen and oxygen only.
(a) An organic compound V has the following composition by mass.
C, 48.65%; H, 8.11%; O, 43.24%
Calculate the empirical formula of compound V.
(b) Compound W has the empirical formula CH4O and a relative molecular mass of 32.
Calculate the molecular formula of compound W.
（June 2021）
(a)
M1 4.05 8.11 2.7
M2 1.5 : 3 : 1 OR 6 : 3 : 2
M3 C3H6O2
(b) (Mr of CH4O = 32) CH4O
Containers for fuel rods in nuclear reactors are made of zirconium.
Nuclear reactors are used to produce energy and to make radioactive isotopes.
(i) Which isotope of a different element is used as a fuel in nuclear reactors?
(ii) State one medical and one industrial use of radioactive isotopes
[1]
235U / 239Pu
NOTE: need symbol or name and nucleon number
[1]
[1]
[2]
(ii) treating cancer / chemotherapy / radiographs / tracer studies / x–ray (scans) /
sterilise surgical instruments / diagnose or treat thyroid disorders / radiotherapy
paper thickness / steel thickness / radiographs / welds / tracing / fill levels in
packages / food irradiation / smoke detectors
ACCEPT: any other uses
N2 + 3H2 ><(reversible) 2NH3
The forward reaction is exothermic. State the effect, if any, on the position of the equilibrium when the following changes are made. Explain your answers. temperature is reduced：
pressure is reduced：
(2022 winter)
Reduced Temperature:
M1 (position of) equilibrium moves to right-hand side
M2 reaction is exothermic
Reduced pressure:
M3 (position of) equilibrium moves to left-hand side
M4 more (gaseous) moles on left-hand side
Which chemist created the periodic table?
(2 for name, 2 for nationality, 1 for when)
The periodic table was invented by Russian chemist Dmitri Mendeleev in 1869.