9. Human saliva has a pH value of approximately 6.8, and can be considered a: a.

Question

9. Human saliva has a pH value of approximately 6.8, and can be considered a: a. strong base K weak acid c. strong acid d. weak base 10. The following reaction will occur: a. non -spontaneously b. spontaneously c. reaction is temperature dependent 11. The following reaction a. occurs spontaneously b. is temperature dependent C. occurs non -spontaneously 12. Which of the following adjustments would NOT cause a reaction to proceed faster? a. changing all reactants to the liquid phase b. increasing the temperature of the reaction c. using a greater amount (high concentration) of reactants d. using only covalent reactants 13. All of the following reaction conditions would generally increase the rate of a chemical reaction, EXCEPT: a. changing the reactants from a liquid state to a gas state. b. increasing the temperature of the reaction c. addition of a catalyst d. increasing the concentration of the reactant species

Explanation / Answer

9. pH less than 7 represents an acid. pH of 6.8 is close to 7 (which is pH of nutral water). Hence saliva can be considered as weak acid. The correct option is b.
10. In this reaction, 110 kcal of heat must be supplied. Thus it is an endothermic reaction. hence, it will occur non-spontaneously. Thus, the option a is the correct answer.
11. In this reaction, 88 kcal of heat must be supplied. Thus it is an endothermic reaction. hence, it will occur non-spontaneously. Thus, the option c is the correct answer.
12.Using only covalent reactants will not cause a reaction to proceed faster. Thus, the option d is the correct anwer.
13. When the reactants are changed from a liquid state to a gas state, the rate of reaction may not increase. Thus, the option a. is the correct answer.

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