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- Explain why there is effervescence when lemon juice is added to sodium hydrogen carbonate. ...(Solved)
Explain why there is effervescence when lemon juice is added to sodium hydrogen carbonate.
Date posted: August 5, 2019. Answers (1)
- The diagram below represents the Haber process for the manufacture of ammonia. Study it and answer the questions that follow.(Solved)
The diagram below represents the Haber process for the manufacture of ammonia. Study it and answer the questions that follow.
a) Name any two impurities removed by the purifier.
b) The catalyst used in the process is finely divided iron. Why iron is finely divided?
c) In the Haber process the conversion of nitrogen and hydrogen into ammonia is only 10%.
The remaining unreacted gases are recycled. What is the advantage of this.
d) A part from iron catalyst and pressure of 500 atmospheres, name any other condition required for this process.
Date posted: August 5, 2019. Answers (1)
- The table below gives some elements of the periodic table and their atomic masses, atomic numbers and melting points. The letters are not the actual...(Solved)
The table below gives some elements of the periodic table and their atomic masses, atomic numbers and melting points. The letters are not the actual symbols of the elements.
(a) Select two elements with oxidation states of -3.
(b) Which elements represent the most powerful reducing agent? Explain.
(c) Which element has the highest ionization energy?
(d) Select two elements which when reacted form a compound that conducts electricity both in molten and aqueous state.
(e) Select any two elements which when reacted form a compound that dissolves in water to form an acidic solution.
(f) Using dots (●) and crosses (X) to represent electrons; draw diagrams to show bonding between B and J.
(g) Explain why for some elements the atomic mass is not twice the atomic number.
(h) Explain why the melting point of element K is higher than that of element D.
(i) Describe how a solid mixture of the Sulphate of element K and lead (II) Sulphate can be separated.
Date posted: August 5, 2019. Answers (1)
- Give the elements that constitute to water gas as a compound and draw the structure of the compound.(Solved)
Give the elements that constitute to water gas as a compound and draw the structure of the compound.
Date posted: July 7, 2019. Answers (1)
- Explain why the boiling and melting point of alkali metals decrease down the group as the halogens increase down the group(Solved)
Explain why the boiling and melting point of alkali metals decrease down the group as the halogens increase down the group
Date posted: June 28, 2019. Answers (1)
- RCOO- Na+ and RC6H5SO3- Na+, represent two cleansing agents where R is a long hydrocarbon chain.
Write the formulae of the salts that would be...(Solved)
R COO─ Na+ and RC6H5SO3─ Na+, represent two cleansing agents where R is a long hydrocarbon chain.
Write the formulae of the salts that would be formed when each of these cleansing agents is added to water containing calcium ions.
Date posted: June 24, 2019. Answers (1)
- State two similarities between rusting and combustion. (Solved)
State two similarities between rusting and combustion.
Date posted: June 24, 2019. Answers (1)
- In an experiment to determine the percentage purity of the sample of
sodium carbonate produced in the Solvay process, 2.15 g of the
sample reacted completely with...(Solved)
In an experiment to determine the percentage purity of the sample of
sodium carbonate produced in the Solvay process, 2.15 g of the
sample reacted completely with 40.0cm3 of 0.5 M sulphuric acid.
I calculate the number of moles of sodium carbonate that
reacted.
II Determine the percentage of sodium carbonate in the
sample. (Na= 23.0, C= 12.0, O = 16.0)
Date posted: June 24, 2019. Answers (1)
- 0.84 g of aluminium reacted completely with chlorine gas.
Calculate the volume of chlorine gas used (Molar gas volume is 24dm3, al = 27).(Solved)
0.84 g of aluminium reacted completely with chlorine gas.
Calculate the volume of chlorine gas used (Molar gas volume is 24dm3, al = 27).
Date posted: June 24, 2019. Answers (1)
- When aluminium oxide was electrolysed, 1800kg of aluminium metal were
obtained.
a) Write equation for the formation of aluminium metal
b) Calculate the quantity of electricity in faradays...(Solved)
When aluminium oxide was electrolysed, 1800kg of aluminium metal were
obtained.
a) Write equation for the formation of aluminium metal
b) Calculate the quantity of electricity in faradays used (Al=27)
Date posted: June 24, 2019. Answers (1)
- A sample of biogas contains 35.2% by mass of methane. A biogas cylinder
contains 5.0 kg of the gas.
Calculate the;
(i) Number of moles of methane in...(Solved)
A sample of biogas contains 35.2% by mass of methane. A biogas cylinder
contains 5.0 kg of the gas.
Calculate the;
(i) Number of moles of methane in the cylinder. (Molar mass of methane=16)
(ii) Total volume of carbon (IV) oxide produced by the combustion of methane in the
cylinder (Molar gas Volume=24.0 dm-3+ at room temperature and pressure).
Date posted: June 24, 2019. Answers (1)
- In an experiment to determine the percentage of magnesium hydroxide in an anti-acid, a
solution containing 0.50 g of the anti-acid was neutralized by 23.0 cm3...(Solved)
In an experiment to determine the percentage of magnesium hydroxide in an anti-acid, a
solution containing 0.50 g of the anti-acid was neutralized by 23.0 cm3 of 0.010m
hydrochloric acid (Relative formula mass of magnesium hydroxide =58)
a) Mass of magnesium hydroxide in the anti-acid;
b) Percentage of magnesium hydroxide in the anti-acid
Date posted: June 24, 2019. Answers (1)
- When 1.08g of aluminum foil were heated in a stream of chlorine gas, the mass of the
product formed was 3.47 g
Calculate the:
(i) Maximum mass of...(Solved)
When 1.08g of aluminum foil were heated in a stream of chlorine gas, the mass of the
product formed was 3.47 g
Calculate the:
(i) Maximum mass of the product formed if chlorine was in excess;
(Al= 27; Cl = 35.5)
(ii) Percentage yield of the product formed
Date posted: June 24, 2019. Answers (1)
- Calculate the mass of nitrogen present if a 25kg bag contained pure
ammonium phosphate, (NH4)2 HPO4. (N = 14.0, H=1.0, P = 31.0, O =16.0(Solved)
Calculate the mass of nitrogen present if a 25kg bag contained pure
ammonium phosphate, (NH4)2 HPO4. (N = 14.0, H=1.0, P = 31.0, O =16.0
Date posted: June 24, 2019. Answers (1)
- The relative molecular mass of one of the fullerenes is 720. What is the
molecular formula of this fullerene? (C=12.00(Solved)
The relative molecular mass of one of the fullerenes is 720. What is the
molecular formula of this fullerene? (C=12.00
Date posted: June 24, 2019. Answers (1)
- Compounds A and B have the same molecular formula C3H6O2. Compound A
liberates carbon (IV) oxide on addition of aqueous sodium carbonate while
compound B does not....(Solved)
Compounds A and B have the same molecular formula C3H6O2. Compound A
liberates carbon (IV) oxide on addition of aqueous sodium carbonate while
compound B does not. Compound B has a sweet smell. Draw the possible
structures of:
(i) Compound A
ii) Compound B
Date posted: June 24, 2019. Answers (1)
- 6.84g of aluminium sulphate were dissolve in 150cm3 of water. Calculate the molar
concentration of the sulphate ions in the solution. (Relative formula mass of aluminium
sulphate...(Solved)
6.84g of aluminium sulphate were dissolve in 150cm3 of water. Calculate the molar
concentration of the sulphate ions in the solution. (Relative formula mass of aluminium
sulphate is 342)
Date posted: June 24, 2019. Answers (1)
- The relative formula mass of a hydrocarbon is 58. Draw and name two possible
structures of the hydrocarbon (C=12.0; H=1.0)(Solved)
The relative formula mass of a hydrocarbon is 58. Draw and name two possible
structures of the hydrocarbon (C=12.0; H=1.0)
Date posted: June 24, 2019. Answers (1)
- The volume of a sample of nitrogen gas at a temperature of 291 K and 1.0x105
Pascal’s was 3.5 x 10-2m3. Calculate the temperature at which...(Solved)
The volume of a sample of nitrogen gas at a temperature of 291 K and 1.0x105
Pascal’s was 3.5 x 10-2m3. Calculate the temperature at which the volume of the
gas would be 2.8 x 10-2m3 at 1.0 x 105 Pascal.
Date posted: June 24, 2019. Answers (1)
- 15.0cm3 of ethanoic acid (CH3COOH) was dissolved in water to make 500cm3 of
solution. Calculate the concentration of the solution in moles per litre.
(C=12.0;H=1.0;O=16.0; density of...(Solved)
15.0cm3 of ethanoic acid (CH3COOH) was dissolved in water to make 500cm3 of
solution. Calculate the concentration of the solution in moles per litre.
(C=12.0;H=1.0;O=16.0; density of ethanoic acid is 1.05 g/cm3)
Date posted: June 24, 2019. Answers (1)