This question is about tests for some elements and compounds.(a) What is the test for hydrogen?(b) The diagram shows hydrogen burning in air, and how some of the gases passing throughthe apparatus are collected and tested.A colourless liquid collects in the U- shaped tube and the limewater turns cloudy very slowly.(i) Describe a chemical test to show that the colorless liquid contains water.testresult(ii) Describe a physical test to show that the colourless liquid is pure water.testresult
Question
This question is about tests for some elements and compounds.(a) What is the test for hydrogen?(b) The diagram shows hydrogen burning in air, and how some of the gases passing throughthe apparatus are collected and tested.A colourless liquid collects in the U- shaped tube and the limewater turns cloudy very slowly.(i) Describe a chemical test to show that the colorless liquid contains water.testresult(ii) Describe a physical test to show that the colourless liquid is pure water.testresult
Solution
(a) The test for hydrogen is to bring a lit splint near the opening of the test tube containing the gas. If the gas is hydrogen, it will burn with a 'pop' sound.
(b)(i) A chemical test to show that the colorless liquid contains water is the anhydrous copper(II) sulfate test. In this test, white anhydrous copper(II) sulfate turns blue when it comes into contact with water.
Test: Add a small amount of anhydrous copper(II) sulfate to the liquid. Result: If the liquid contains water, the anhydrous copper(II) sulfate will turn from white to blue.
(ii) A physical test to show that the colorless liquid is pure water is to check its boiling point. Pure water has a boiling point of 100 degrees Celsius at standard atmospheric pressure.
Test: Heat the liquid and measure its boiling point using a thermometer. Result: If the liquid is pure water, it will boil at 100 degrees Celsius.
Similar Questions
A student found this information about hydrogen.(a) (i) The student repeated Boyle’s experiment using iron and dilute sulfuric acidState two observations that he could have made1.2.(iii) Complete the word equation for this reaction.Iron + sulfuric acid → +(b) Balance the equation for the complete combustion of hydrogen.H2 + O2 → H2O(c) To show that the liquid produced by burning hydrogen was pure water, a student carried out achemical test and a physical test.(i) The chemical test involves adding a few drops of the liquid to a sample of anhydrous copper(II) sulfate. State the colour change observed.Initial colourFinal colour(ii) Place a cross ( ) in one box to show the formula of the compound formed in this chemical test. A Cu(OH ) 2 B CuSO4 C CuSO4H2O D CuSO4 . 5H2O(iii) The physical test involved measuring a property of the liquid.State a suitable physical property and give the value for pure water.Physical propertyValue(c) (i) suggest what property of hydrogen makes it suitable for filling balloons.(iii) Helium is now used instead of hydrogen to fill balloons.State the property of helium that makes it more suitable than hydrogen for filling balloons.(d) Write an equation, including state symbols, to show the process that occurs when hydrogen isliquefied.Ammonium chloride contains oppositely charged ions(a) State the formula of each ionPositive ionNegative ion(b) (i) Describe a chemical test to show that a substance contains ammonium ions.(ii) describe a chemical test to show that a substance contains chloride ions.(c) Ammonium chloride decomposes when heated:NH4CI(s) ⇄ NH3(g) + HCI(g)What does the ⇄ symbol indicate about the reaction?(d) The reaction between ammonia and hydrogen chloride can be used to illustrate diffusion withthe following apparatus.After a few minutes, a white solid appears inside the tube(i) Identify the white solid(ii) What does the diagram show about the speed of the ammonia molecules compared to thespeed of the hydrogen chloride molecules?(e) State the main hazard when using concentrated hydrochloric acid in the experiment in (d)suggest one precaution you could use to minimise this hazard.HazardPrecaution
Describe how to test the gas to show that it is hydrogen
Q2. How will you test for the gas which is liberated when HCL reacts with an active metal?
Describe a test to identify the gas used to sterilise water. [2 marks] Test Result
Which answer would provide the most detailed and accurate description of the observations for this reaction?Group of answer choicesThe test tube contains both a white, cloudy liquid and a clear, colorless liquid.The test tube contains a white liquid and a clear, colorless solid.The test tube contains a white solid floating in a clear, colorless liquid.The test tube contains a clear, colorless liquid with a white solid that has sunk to the bottom.
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