Regents Chemistry Test Preparation Practice

    Acidity Ph And Indicators

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    Base your answers to questions 8 on the information below.

    Vitamin C, also known as ascorbic acid, is water soluble and cannot be produced by the human body. Each day, a person’s diet should include a source of vitamin C, such as orange juice. Ascorbic acid has a molecular formula of C6H8O6 and a gram-formula mass of 176 grams per mole.

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    Base your answers to questions 9 on the information below.

    The active ingredient in the pain reliever aspirin is acetylsalicylic acid. This compound can be produced by reacting salicylic acid with acetic acid. The label of one aspirin bottle indicates that the accepted mass of acetylsalicylic acid in each tablet is 325 milligrams.

    In a laboratory, an aspirin tablet is crushed and mixed with water to dissolve all of the acetylsalicylic acid. The measured pH of the resulting solution is 3.0.

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    Base your answers to questions 10 on the information below and on your knowledge of chemistry.

    Baking soda, NaHCO3, can be commercially produced during a series of chemical reactions called the Solvay process. In this process, NH3(aq), NaCl(aq), and other chemicals are used to produce NaHCO3(s) and NH4Cl(aq).

    To reduce production costs, NH3(aq) is recovered from NH4Cl(aq) through a different series of reactions. This series of reactions can be summarized by the overall reaction represented by the unbalanced equation below.

    NH4Cl(aq) + CaO(s) → NH3(aq) + H2O(ℓ) + CaCl2(aq)

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    Base your answers to questions 11 on the information below and on your knowledge of chemistry.

    The pH of various aqueous solutions are shown in the table below.

    acids-bases-and-salts, acidity-ph-and-indicators fig: chem12015-exam_g18.png

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    Base your answers to questions 12 on the information below and on your knowledge of chemistry.

    The hydrangea is a flowering plant. The color of the flowers it produces can change depending on the pH value of the soil in which the plant grows. Adding aluminum sulfate makes the soil more acidic and adding calcium hydroxide makes the soil more basic.

    A student performed an experiment by varying soil pH and recording the color of the flowers. The following table summarizes the results of the experiment.

    acids-bases-and-salts, acidity-ph-and-indicators fig: chem12017-exam_g18.png

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    Base your answers to questions 14 on the information below.

    The diagram below shows typical pH values found in four parts of the human digestive system. In the small intestine, the enzyme lipase acts as a catalyst, increasing the rate of fat digestion.

    acids-bases-and-salts, acidity-ph-and-indicators, acids-bases-and-salts, acidity-ph-and-indicators fig: chem62012-exam_g24.png

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    Base your answers to questions 15 on the information below and on your knowledge of chemistry.

    A scientist bubbled HCl(g) through a sample of H2O(ℓ). This process is represented by the balanced equation below.

    H2O(ℓ) + HCl(g) → H3O+(aq) + Cl(aq)

    The scientist measured the pH of the liquid in the flask before and after the gas was bubbled through the water. The initial pH value of the water was 7.0 and the final pH value of the solution was 3.0.

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