Nelson Science Perspectives 10
1st Edition
ISBN: 9780176355289
Textbook solutions
All Solutions
Page 281: Check Your Understanding
Exercise 1
Step 1
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a. A solution is said to be neutral if its pH is 7.
Step 2
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b. The pH of the base is 12. As acid is added to the flask containing the base, the pH of the solution decreases gradually until it reaches 7. This point is the point of neutralization. Addition of acid beyond this point will further reduce the pH to a value equal to that of the acid.
Exercise 2
Step 1
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a.
Balanced chemical equation:
$$
mathrm{HCl_{(aq)} + KOH_{(aq)} longrightarrow KCl_{(aq)} + H_2O_{(aq)}}
$$
Step 2
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b.
Balanced chemical equation:
$$
mathrm{H_2SO_{4(aq)} + 2KOH_{(aq)} longrightarrow K_2SO_{4(aq)} + 2H_2O_{(aq)}}
$$
Result
3 of 3
Click to see equations.
Exercise 3
Step 1
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a.
Balanced chemical equation:
$$
mathrm{H_2CO_{3(aq)} + 2KOH_{(aq)} longrightarrow K_2CO_{3(aq)} + 2H_2O_{(aq)}}
$$
Step 2
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b. The pH of KOH solution increases as carbonic acid is added to it. The pH continues to increase until it becomes 7. Further addition of carbonic acid will further reduce the pH to below 7.
Result
3 of 3
Click to see answers.
Exercise 4
Step 1
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The large acid spill can be neutralized using both sodium hydroxide and baking soda. Sodium hydroxide is however a very strong base and its reaction with any acid will release large amounts of heat as this reaction is exothermic in nature. Therefore, it is recommended to use baking soda to neutralize the acid spill.
Step 2
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Note: Acid spills are usually flushed out using large amounts of water. Acid base reactions are exothermic and release energy that can affect/erode the area of spill.
Exercise 5
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Phenolphthalein is pink in basic medium and colourless in acidic medium. Lemon juice is acidic in nature and therefore phenolphthalein turns colorless in that medium and therefore the insides of the lemon were not pink.
Exercise 6
Solution 1
Solution 2
Step 1
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$textbf{Calcium oxide(CaO)}$, known as ¨lime¨, is a principal ingredient in making cement, and it’s the basis in concrete and mortars.
Step 2
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CaO reacts forcefully in water creating a chemical called Ca(OH)₂, which is corrosive and should be avoided in direct contact with the human body.
Cement dust is also unhealthy and can irritate your lungs, respiratory system, and skin so the proper use of protection should be worn when working with cement.
Proper protection should be used when working with Calcium Oxide.
Cement dust is also unhealthy and can irritate your lungs, respiratory system, and skin so the proper use of protection should be worn when working with cement.
Proper protection should be used when working with Calcium Oxide.
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In the question we will explain the characteristics of CaO and what precautions should the bricklayer do when mixing cement and why.
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CaO is a basic material, and highly corrosive when mixed with water.
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Wear protective clothing such as gloves, eye goggles, face mask, otherwise, it leads to skin irritation, eye damage, or respiratory problems.
Exercise 7
Step 1
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a.
Acids react with calcium carbonate to form a calcium salt, water and carbon dioxide gas.
Acids react with calcium carbonate to form a calcium salt, water and carbon dioxide gas.
Step 2
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b.
Balanced chemical equation:
$$
mathrm{CaCO_{3(s)} + H_2SO_{4(aq)} longrightarrow CaSO_{4(aq)} + H_2O_{(l)}+CO_{2(g)}}
$$
Step 3
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c. This reaction will adversely affect the population of corals. Their shells will react with the acid to erode. This will damage their hard covering and will expose the inner body of these to the environment, further posing a threat to their existence.
Result
4 of 4
Click to see answers.
Exercise 8
Step 1
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The salt formed is sodium sulfate. This is only possible if the base used was sodium hydroxide. Balance chemical equation for proof:
$$
mathrm{2NaOH_{(aq)} + H_2SO_{4(aq)} longrightarrow Na_2SO_{4(aq)} + 2H_2O_{(l)}}
$$
Result
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Sodium hydroxide is the base used here.
Exercise 9
Result
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The acid in lemon juice neutralizes the base in fish muscles to salt and water, making the odor go away.
Exercise 10
Step 1
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Calcium carbonate deposit in heating elements can be removed by cleaning these with an acid (like vinegar or lemon juice). This acid will react the calcium carbonate to produce salt, water and carbon dioxide gas.
Equation:
Equation:
$$
mathrm{2HX_{(aq)} + CaCO_{3(s)} longrightarrow CaX_{2(aq)} + H_2O_{(aq)}+CO_{2(g)}}
$$
Here X is the anion in the acid.
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