- Brine usually contains soluble calcium and magnesium salts. Explain how sodium carbonate is used to purify brine(Solved)
Brine usually contains soluble calcium and magnesium salts. Explain how sodium carbonate is used to purify brine
Date posted: February 16, 2017. Answers (1)
- During purification of copper by electrolysis, 1.48 g of copper were deposited when current was passed through aqueous copper (II) sulphate for 2$\frac{1}{2}$ hours. Calculate the amount of current used. (Cu = 63.5; 1 F = 96500 C(Solved)
During purification of copper by electrolysis, 1.48 g of copper were deposited when current was passed through aqueous copper (II) sulphate for 2$\frac{1}{2}$ hours. Calculate the amount of current used. (Cu = 63.5; 1 F = 96500 C).
Date posted: February 16, 2017. Answers (1)
- An element P has a relative atomic mass of 88. When a current of 0.5 amperes was passed through the fused chloride of P for 32 minutes and 10 seconds, 0.44 g of P were deposited at the cathode.(Solved)
An element P has a relative atomic mass of 88. When a current of 0.5 amperes was passed through the fused chloride of P for 32 minutes and 10 seconds, 0.44 g of P were deposited at the cathode. Determine the charge on an ion of P.
(1 Faraday = 96500 Coulombs)
Date posted: February 16, 2017. Answers (1)
- When a current of 1.5 amperes was passed through a cell containing M3+ ions of metal M for 15 minutes, the mass of the cathode increases by 0.26 g. (1 Faraday = 96500 coulombs). (Solved)
When a current of 1.5 amperes was passed through a cell containing M3+ ions of metal M for 15 minutes, the mass of the cathode increases by 0.26 g. (1 Faraday = 96500 coulombs).
a) Calculate the quantity of electricity used
b) Determine the relative atomic mass of metal M.
Date posted: February 16, 2017. Answers (1)
- Give reason why aluminium metal would protect iron from rusting better than zinc metal(Solved)
Give reason why aluminium metal would protect iron from rusting better than zinc metal.
Date posted: February 16, 2017. Answers (1)
- Aqueous potassium sulphate was electrolyzed using platinum electrodes in a cell......(Solved)
Aqueous potassium sulphate was electrolyzed using platinum electrodes in a cell.
a) Name the products formed at the cathode and anode
b) How does the concentration of the electrolyte change during electrolysis?
c) Why would it not be advisable to electrolyse aqueous potassium sulphate using potassium metal electrodes?
Date posted: February 16, 2017. Answers (1)
- State two factors that determine the rate of a reaction(Solved)
Other than concentration, state two factors that determine the rate of a reaction.
Date posted: February 16, 2017. Answers (1)
- Why is it not advisable to use aqueous sodium chloride solution as the salt bridge in the electrochemical cell formed between half cells..(Solved)
Explain why it is not advisable to use aqueous sodium chloride solution as the salt bridge in the electrochemical cell formed between half cells, Pb2+(aq)/Pb(s) Eo = - 0.13 V and Cu2+(aq)/Cu(s) Eo = + 0.34 V.
Date posted: February 16, 2017. Answers (1)
- State two factors that determine the rate of a chemical(Solved)
Other than temperature, state two factors that determine the rate of a chemical
Date posted: February 16, 2017. Answers (1)
- State the Le Chatelier's principle(Solved)
State the Le Chatelier's principle.
Date posted: February 15, 2017. Answers (1)
- What condition is necessary for equilibrium to established (b) When calcium carbonate is heated, the equilibrium shown below is established (Solved)
a) What condition is necessary for equilibrium to established
b) When calcium carbonate is heated, the equilibrium shown below is established
CaCO3(s) $_{\leftarrow}^{\rightarrow}$ CaO(s) + CO2(g)
How would the position of equilibrium be affected if a small amount of dilute potassium hydroxide is added to the equilibrium mixture? Explain.
Date posted: February 15, 2017. Answers (1)
- State and explain how the rate of reaction between zinc granules and steam can be increased(Solved)
State and explain how the rate of reaction between zinc granules and steam can be increased.
Date posted: February 15, 2017. Answers (1)
- A dynamic equilibrium between dichromate and chromate ions is established as shown in the equation below(Solved)
A dynamic equilibrium between dichromate and chromate ions is established as shown in the equation below.
Cr2O$^{2-}_7$(aq) + 2OH-(aq) $^{\rightarrow}_{\leftarrow}$ 2CrO$_4^{2-}$(aq) + H2O(l)
a) What is meant by dynamic equilibrium?
b) State and explain the observation that would be made if a few pellets of potassium hydroxide are added to the equilibrium mixture.
Date posted: February 15, 2017. Answers (1)
- The decomposition of calcium carbonate can be represented by the equation:(Solved)
The decomposition of calcium carbonate can be represented by the equation:
CaCO3(s) $_{\rightarrow}^{\leftarrow}$ CaO(s) + CO2(g)
Explain how an increase in pressure would affect the equilibrium position.
Date posted: February 15, 2017. Answers (1)
- When bromine gas reacts with aqueous sodium hydroxide, the equilibrium represented by the equation:(Solved)
When bromine gas reacts with aqueous sodium hydroxide, the equilibrium represented by the equation:
Br2(aq) + 2OH-(aq) $_{\leftarrow}^{\rightarrow}$ Br-(aq) + OBr-(aq) + H2O(l) is established. What observations would be made if a few drops of sulphuric (VI) acid were added to the equilibrium mixture? Explain.
Date posted: February 15, 2017. Answers (1)
- What is meant by lattice energy?(Solved)
What is meant by lattice energy?
Date posted: February 15, 2017. Answers (1)
- State the Hess's Law and its applications(Solved)
State the Hess's Law and its applications.
Hess's law States that if a chemical change can be made to take place in two or more steps, the amount of the total heat change is the same no matter which method is used.
Its applications are:
1.Determination of heat of formation of substances which cannot be measured experimentally. Substances like methane,carbon dioxide and benzene cannot be prepared by uniting there elements. Therefore it is not possible to measure the heat of formation of certain compound directly.
2.Determination of heat of transition. The heat of transition from one allotropic form to another can also be calculated with the help of Hess's law.
3.Determination of heat of various reaction. By using Hess's law we can calculate enthalpies of many reactions which can not be measured directly. For example the enthalpy of dimerization of nitrogen dioxide.
Date posted: February 15, 2017. Answers (1)
- What is the meaning of molar heat of combustion?(Solved)
What is meant by molar heat of combustion?
Date posted: February 15, 2017. Answers (1)
- Write an ionic equation for the reaction that took place(Solved)
A beaker contained 75.0 cm3 of aqueous copper (II) sulphate at 23.7oC. When scrap iron metal was added to the solution, the temperature rose to 29.3oC.
Write an ionic equation for the reaction that took place
Date posted: February 15, 2017. Answers (1)
- What is the name given to each of the following:(Solved)
What is the name given to each of the following:
a) Ability of a metal to be made into wire
b) Minimum energy required for a chemical reaction to start;
c) Type of force that holds atoms of neon together?
Date posted: February 15, 2017. Answers (1)