This question is about gases - Edexcel - GCSE Chemistry Combined Science - Question 6 - 2022 - Paper 1
Question 6
This question is about gases.
(a) When sodium is added to water, hydrogen gas is produced.
Which observation shows that a gas has been produced?
A a white precip... show full transcript
Worked Solution & Example Answer:This question is about gases - Edexcel - GCSE Chemistry Combined Science - Question 6 - 2022 - Paper 1
Step 1
Which observation shows that a gas has been produced?
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The correct answer is B: effervescence is seen. This indicates the release of gas, which creates bubbles in the liquid.
Step 2
Which gas bleaches damp litmus paper?
99%
104 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The gas that bleaches damp litmus paper is B: chlorine. Chlorine is a strong oxidizing agent and can decolorize the dye in litmus paper.
Step 3
Calculate the mass of carbon dioxide that has been released.
96%
101 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
To find the mass of carbon dioxide released, subtract the mass remaining from the initial mass:
Initial mass of calcium carbonate = 5.000 g
Mass remaining = 2.800 g
Mass of CO₂ released = 5.000 g - 2.800 g = 2.200 g
Thus, the mass of carbon dioxide released is 2.20 g.
Step 4
Explain, using Figure 9, why helium is inert.
98%
120 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Helium is inert because it has a complete outer electron shell. It contains two electrons, which fill its outer shell, making it stable and unreactive. Helium does not gain, lose, or share electrons.
Step 5
State one property of helium, apart from it being inert, that makes it suitable for filling balloons.
97%
117 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
One property of helium that makes it suitable for filling balloons is that it is less dense than air. This allows the balloon to float.
Step 6
Explain how the relative amount of each of the gases in Figure 10 has increased or decreased over time.
97%
121 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The relative amounts of these gases have changed due to several natural processes and human activities:
Carbon Dioxide: Initially high due to volcanic activity; however, reductions have occurred due to absorption by oceans and plants.
Water Vapour: Large amounts condensed to form water, reducing its proportion in the atmosphere.
Oxygen: Levels increased over time due to photosynthesis, where plants convert carbon dioxide into oxygen, raising its concentration.
