-
How long would 200 cm3 of Hydrogen chloride take to diffuse through a porous plug if carbon(IV)oxide takes 200 seconds to diffuse through?
Date posted:
February 15, 2019
-
An element Q reacts with dilute acids but not with cold water. Element R does not react with dilute acids. Element S displaces element P from its oxides. P reacts with cold water. Arrange the four metals in order of their reactivity starting with the most reactive.
Date posted:
February 13, 2019
-
The use of materials of lead in roofing and in water pipes is being discouraged.
State
(i)Two reasons why these materials have been used in the past.
(ii)One reason why their use is being discouraged.
Date posted:
February 13, 2019
-
Calculate the number of atoms present in:(Avogadros constant L = 6.0 x 10 23) 0.23 g of dilute sulphuric (VI)acid
Date posted:
February 5, 2019
-
Oxygen gas takes 250 seconds to diffuse through a porous diaphragm. Calculate the molar mass of gas Z which takes 227 second to diffuse.
Date posted:
February 5, 2019
-
How long would 200cm3 of Hydrogen chloride take to diffuse through a porous plug if carbon(IV)oxide takes 200seconds to diffuse through?
Date posted:
February 5, 2019
-
It takes 30 seconds for 100cm3 of carbon(IV)oxide to diffuse across a porous plate. How long will it take 150cm3 of nitrogen(IV)oxide to diffuse across the same plate under the same conditions of temperature and pressure?
(C=12.0,N=14.0=16.0)
Date posted:
February 5, 2019
-
State Grahams law of diffusion and show its mathematical formula
Date posted:
February 5, 2019
-
A fixed mass of gas at 102300Pa pressure has a volume of 25cm3. Calculate its volume if the pressure is doubled.
Date posted:
February 5, 2019
-
How many atoms of each element are present in each of the following compounds? Lithium chloride
Date posted:
January 7, 2019
-
Explain why bromine is a liquid at room temperature while chlorine is a gas
Date posted:
January 3, 2019
-
Starting with zinc oxide, describe how you can prepare a sample of lead ii sulphate
Date posted:
January 2, 2019
-
In an experiment a piece of magnesium ribbon was cleaned with steel wool 2.4g of the clean ribbon was placed in a crucible and completely burnt in oxygen.after cooling the product weighted 4.0g.
(a)explain why it was necessary to clean the magnesium ribbon?
(b)what observation was made in the crucible after burning?
(c)why was there an increase in mass?
(d)write the equation for reaction which took place in the crucible?
(e)the product in the crucible was shaken with water and filtered. Explain the observation which was made when blue and red litmus papers were dropped into the filtrate.
Date posted:
December 30, 2018
-
A student crushed the seeds and then added propane instead of water to extract oil from castor oil seeds. Why did he use propane instead of water and why were the seeds first crushed?
Date posted:
December 26, 2018
-
A hydrocarbon consist of 92.3% carbon. Its molecular mass is 26. Calculate its molecular formula.
Date posted:
December 16, 2018
-
What happens when ammonium chloride is heated?
Date posted:
December 12, 2018
-
Crystals of sodium carbonate decahydrate were exposed to air for about four days
1. State what was observed
2. Name the process that took place
3. Write an equation for the reaction that occurred
Date posted:
December 11, 2018
-
When a few drops of potassium permanganate are added to an aqueous solution of ferrous sulphate, solution turns brown. On the other hand, when the test is repeated using sodium molybdate instead of potassium permanganate no similar colour change is observed.
Date posted:
November 29, 2018
-
What are the ingredients used to make soap?
Date posted:
November 21, 2018
-
Explain why the ionic radius of potassium is greater than that of sodium.
Date posted:
November 14, 2018
-
With reference to chlorine, distinguish between covalent bond and van der Waals forces.
Date posted:
November 7, 2018
-
Explain why graphite is a poor conductor of electricity at high temperature
Date posted:
October 8, 2018
-
Calculate the number of chloride ions in a 250cm3 of 1M solution calcium chloride (Avogadro’s number is 6.0 × 1023)
Date posted:
August 19, 2018
-
Distinguish between a strong acid and a concentrated acid
Date posted:
August 19, 2018
-
In an experiment it was found that 40.0cm3 of 0.2M sodium hydroxide solution just neutralized 0.2g of a dibasic acid Q. Calculate the relative molecular mass of acid Q.
Date posted:
August 19, 2018
-
A student was asked to prepare Lead (II) chloride salt using the following ingredients; Nitric (V) acid, lead (II) oxide and hydrochloric acid. Using ionic equations only explain how the salt can be prepared.
Date posted:
August 19, 2018
-
Paper chromatography is a method of separating colours or dyes.
What two properties should the components of a mixture have that would make the separation possible
Date posted:
August 19, 2018
-
Dilute nitric acid is added to excess green solid. Effervescence occurs and a blue solution is formed. When excess ammonia solution is added to a sample of the solution a deep blue solution is formed.
Identify the anion and cation in the green solid.
Date posted:
August 18, 2018
-
Nitrogen (IV) Oxide is passed through a combustion tube before Copper is heated. Give a reason.
Date posted:
August 18, 2018
-
State two distinctive features of dynamic equilibrium
Date posted:
August 17, 2018