Section 5.4: Neutralization Reactions

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Section 5.4: Neutralization Reactions
Mini Investigation: Explaining Disappearing Ink, page 207
A. The magenta colour of the paper faded as the paper dried.
B. The pH of the solution on the paper decreased since the magenta colour became less intense.
C. Carbon dioxide in the air dissolved in the solution, producing carbonic acid which neutralizes
some of the basic solution.
D. The chemical equation for the reaction is: CO2(g) + H2O(l) → H2CO3(aq)
Research This: Neutralizing Hair Care, page 209
A. Hair dyes contain basic compounds that open the cuticle of the hair to allow bleach to enter
the hair shaft and remove the existing colour. If used correctly, other chemicals involved in the
hair dyeing process close the cuticle, returning it to its normal state. If used incorrectly, the
cuticle may not close completely, leaving hair tangled and brittle. In extreme cases, hair dyes can
cause skin irritation, hair loss, and allergic reactions.
B. Answers may vary. Sample answer: Other than the extreme health problems that can occur,
tangled and brittle hair is the most significant problem associated with the use of hair dyes. The
problem can be avoided by having the procedure done by a trained professional.
C. Answers may vary. Some students may say that they feel less comfortable about using
permanent hair dyes.
D. Answers may vary. Students should present their findings in a novel way appropriate for
younger high school students, such as a modern musical, graphic novel, or video presentation.
Research This: Neutralizing a Base, page 210
A. Two substances that could be used to neutralize the sodium hydroxide in drain opener
solution are carbonic acid (in soft drinks) and sodium hydrogen carbonate (baking soda).
The chemical equation for the neutralization of sodium hydroxide using carbonic acid is:
H2CO3(aq) + 2 NaOH(aq) → 2 H2O(l) + Na2CO3(aq)
The chemical equation for the neutralization of sodium hydroxide using sodium hydrogen
carbonate is:
NaHCO3(aq) + NaOH(aq) → H2O(l) + Na2CO3(aq)
B. Protective clothing and eye protection should be worn to prevent accidental contact with the
cleaner. Providing adequate ventilation is also necessary.
C. Answers may vary. Sample answer: I would recommend using sodium hydrogen carbonate
since it is inexpensive, safe to handle, and effective at neutralizing a base spill.
Section 5.4 Questions, page 211
1. (a) 2 HNO3(aq) + Ca(OH)2(aq) → 2 H2O(l) + Ca(NO3)2(aq)
(b) 2 HNO3(aq) + K2CO3(aq) → H2O(l) + CO2(g) + 2 KNO3(aq)
(c) 3 HC2H3O2(aq) + Al(OH)3(s) → 3 H2O(l) + Al(C2H3O2)3(aq)
(d) H3PO4(aq) + 3 NaHCO3(aq) → 3 H2O(l) + 3 CO2(g) + Na3PO4(aq)
(e) 2 H3PO4(aq) + 3 Ca(OH)2(aq) → 6 H2O(l) + Ca3(PO4)2(s)
(f) H2SO4(aq) + Ca(HCO3)2(aq) → 2 H2O(l) + 2 CO2(g) + CaSO4(s)
(g) 2 HClO3(aq) + CaCO3(s) → H2O(l) + CO2(g) + Ca(ClO3)2(aq)
Copyright © 2011 Nelson Education Ltd.
Chapter 5: Chemical Processes
5.4-1
2. The two chemical equations are:
Ba(OH)2(aq) + H2SO4(aq) → 2 H2O(l) + BaSO4(s)
Ba(HCO3)2(aq) + H2SO4(aq) → 2 H2O(l) + 2 CO2(g) + BaSO4(s)
3. (a) Bubbling pressurized carbon dioxide gas into carbonated drinks forms carbonic acid.
(b) The chemical equation for the neutralization reaction is:
H2CO3(aq) + 2 NaOH(aq) → 2 H2O(l) + CO2(g) + Na2CO3(aq)
(c) A carbonated soft drink is more readily available and safer to use than hydrochloric acid.
4. The acidity of the lemon juice neutralizes the basic compounds of the fish, eliminating their
smell.
5. Calcium oxide is a basic oxide which forms calcium hydroxide in water. As this basic solution
flows through the spill site, calcium hydroxide neutralizes the acid spill.
6. Incorporating the neutralizing agent into the absorbent material makes it more convenient to
clean up the spill. This way the spill is neutralized and absorbed in one step. This saves both time
and labour costs.
7. Answers may vary. Sample answer: Acidosis is a condition during which the pH of blood
drops below 7.35. Alkalosis occurs when the blood pH rises above 7.45. Acidosis can be caused
by excess acid in the blood, the loss of hydrogen carbonate ions from the blood (called metabolic
acidosis), or the build-up of carbon dioxide in the blood resulting from slow breathing or
ineffective lung function (respiratory acidosis). Acidosis can occur as a result of poor kidney
function. Respiratory acidosis can occur when poor lung function does not expel as much carbon
dioxide as it should. Acidosis is normally treated with medication. For example, drugs that dilate
the chambers in the lungs promote air flow, allowing more carbon dioxide to be expelled.
Alkalosis can occur due to excess hydrogen carbonate ions in the blood (called metabolic
alkalosis), or from lower than normal levels of dissolved carbon dioxide in blood resulting from
rapid breathing or hyperventilation (respiratory alkalosis). Medical alkalosis can develop when
the body loses too much acid such as during extended periods of vomiting. The most common
cause of rapid breathing is anxiety or stress. These can be treated through relaxation or
medication.
Copyright © 2011 Nelson Education Ltd.
Chapter 5: Chemical Processes
5.4-2
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