- In a class experiment, 5.0g of ethanol were completely burnt and all the heat evolved was used to heat 500cm3 of water from 20o to...(Solved)
In a class experiment, 5.0g of ethanol were completely burnt and all the heat evolved was used to heat 500cm3 of water from 20o to 80oC. (Given that the specific heat capacity of water = 4.18Jg-1oC-1, density of water = 1.0gcm-3, C = 12, O = 16, H = 1.0)
i. Write a balanced equation to show the reaction that takes place when ethanol burns.
ii. Calculate the heat energy:
I. Absorbed by the water
II. Given out when one mole of ethanol was burned completely.
Date posted: November 13, 2019. Answers (1)
- Complete the following nuclear equation(Solved)
(a) Complete the following nuclear equation
(b) 100g of a radioactive substance was reduced to 12.5g within 15.6 years. Determine
the half-life of the substance
Date posted: November 7, 2019. Answers (1)
- Study the information in the following table and answer the questions that follow. The letters do not represent the actual chemical symbols of the elements.(Solved)
Study the information in the following table and answer the questions that follow. The letters do not represent the actual chemical symbols of the elements.
Which of the above elements are:
(i) Likely to be radioactive?
(ii) Able to form a compound with the highest ionic character?
Date posted: November 7, 2019. Answers (1)
- Study the nuclear reactions given and answer the questions that follow:(Solved)
Study the nuclear reactions given and answer the questions that follow:
(a) Write an equation for the nuclear reaction in step II
(b) Give one use of Y
Date posted: November 6, 2019. Answers (1)
- Some two elements are represented as:(Solved)
Some two elements are represented as:
(a) How many protons does X have?
(b) How many neutrons does Y have?
Date posted: November 6, 2019. Answers (1)
- What effect do excessive exposures of radiation have on metals?(Solved)
What effect do excessive exposures of radiation have on metals?
Date posted: November 6, 2019. Answers (1)
- The graph below shows the radioactive decay of a certain nuclide. Determine the half-life of the nuclide(Solved)
The graph below shows the radioactive decay of a certain nuclide. Determine the half-life of the nuclide
Date posted: November 6, 2019. Answers (1)
- Uranium -238 disintegrates by emitting an alpha particle to form substance Y.
Nuclide Y emits a beta particle to form substance Z. Write down nuclear equations...(Solved)
Uranium -238 disintegrates by emitting an alpha particle to form substance Y.
Nuclide Y emits a beta particle to form substance Z. Write down nuclear equations to show how
substance Y and Z are formed (U=At No. 92)
Date posted: November 6, 2019. Answers (1)
- Complete the nuclear equation below:-(Solved)
Complete the nuclear equation below:-
Date posted: November 6, 2019. Answers (1)
- Complete the following equation by determining the values of U and V.(Solved)
Complete the following equation by determining the values of U and V.
Date posted: November 6, 2019. Answers (1)
- The formula given below represents a portion of a polymer(Solved)
The formula given below represents a portion of a polymer
(a) Give the name of the polymer
(b) Draw the structure of the monomer used to manufacture the polymer
Date posted: November 6, 2019. Answers (1)
- Name the class of cleansing agents to which each belongs(Solved)
are two types of cleansing agents;
i) Name the class of cleansing agents to which each belongs
ii) Which one of these agents in (i) above would be more suitable when washing with water from the Indian ocean. Explain
Date posted: November 6, 2019. Answers (1)
- The structure below represents a polymer. Study and answer the questions that follow:-(Solved)
The structure below represents a polymer. Study and answer the questions that follow:-
(i) Name the polymer above
(ii) Determine the value of n if giant molecule had relative molecular mass of 4956
Date posted: November 6, 2019. Answers (1)
- Y grams of a radioactive isotope take 120days to decay to 3.5grams. The half-life period of the isotope is 20 days.
Find the initial mass of...(Solved)
Y grams of a radioactive isotope take 120days to decay to 3.5grams. The half-life period of the isotope is 20 days.
Find the initial mass of the isotope
Date posted: November 6, 2019. Answers (1)
- Substances A and B are represented by the formulae ROH and RCOOH respectively.
They belong to two different homologous series of organic compounds. If both A...(Solved)
Substances A and B are represented by the formulae ROH and RCOOH respectively.
They belong to two different homologous series of organic compounds. If both A and B
react with potassium metal:
(a) Name the common product produced by both
(b) State the observation made when each of the samples A and B are reacted with sodium hydrogen carbonate
(i) A
(ii) B
Date posted: November 6, 2019. Answers (1)
- The scheme below shows some reactions starting with ethanol. Study it and answer the questions that follow:-(Solved)
The scheme below shows some reactions starting with ethanol. Study it and answer the questions that follow:-
Date posted: November 6, 2019. Answers (1)
- (a) Draw the structure of pentanoic acid
(b) Draw the structure and give the name of the organic compound formed when ethanol reacts with pentanoic acid...(Solved)
(a) Draw the structure of pentanoic acid
(b) Draw the structure and give the name of the organic compound formed when ethanol reacts with pentanoic acid in presence of concentrated sulphuric acid
Date posted: November 6, 2019. Answers (1)
- Draw the structural formulae of two compounds that may be reacted to form ethylpropanoate(Solved)
Draw the structural formulae of two compounds that may be reacted to form ethylpropanoate
Date posted: November 6, 2019. Answers (1)
- a) Write an equation showing how ammonium nitrate may be prepared starting with ammonia gas
(b) Calculate the maximum mass of ammonium nitrate that can be...(Solved)
a) Write an equation showing how ammonium nitrate may be prepared starting with ammonia gas
(b) Calculate the maximum mass of ammonium nitrate that can be prepared using 5.3kg of ammonia (H=1, N=14, O=16)
Date posted: November 6, 2019. Answers (1)
- The flow chart below represents a series of reactions starting with ethanoic acid:-(Solved)
The flow chart below represents a series of reactions starting with ethanoic acid:-
(a) Identify substances A and B
(b) Name the process I
Date posted: November 6, 2019. Answers (1)