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 observation indicating the production of a gas is B: effervescence is seen. Effervescence typically indicates the release of a gas as bubbles form.
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 known for its bleaching properties and ability to decolorize litmus.
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, we start with the initial mass of calcium carbonate, which is 5.000g. After heating, the remaining mass is 2.800g.
d = ext{mass of CaCO}_{3} - ext{remaining mass} = 5.000g - 2.800g = 2.200g.
Therefore, the mass of carbon dioxide released is 2.200g.
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 an inert gas because it has a complete outer shell of electrons. Specifically, it has two electrons in its outer shell, fulfilling the octet rule, which means it does not readily gain, lose, or share electrons. This stability leads to its lack of reactivity.
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 property allows helium-filled balloons 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 gases have changed due to natural processes and human activities.
Carbon Dioxide: Initially abundant from volcanic activity, it has decreased due to absorption by oceans and plants.
Water Vapour: It has decreased as water condensed and formed oceans.
Oxygen: Increased significantly due to photosynthesis by plants, which released oxygen as a byproduct.
