Topic: Acidity Ph And Indicators
Acidity Ph And Indicators
Phenolphthalein is pink in an aqueous solution having a pH of
(1) 5
(2) 2
(3) 7
(4) 12
Three samples of the same solution are tested, each with a different indicator. All three indicators, bromthymol blue, bromcresol green, and thymol blue, appear blue if the pH of the solution is
(1) 4.7
(2) 6.0
(3) 7.8
(4) 9.9
What is the color of the indicator thymol blue in a solution that has a pH of 11?
(1) red
(2) blue
(3) pink
(4) yellow
The acidity or alkalinity of an unknown aqueous solution is indicated by its
(1) pH value
(2) electronegativity value
(3) percent by mass concentration
(4) percent by volume concentration
Which statement describes characteristics of a 0.01 M KOH(aq) solution?
(1) The solution is acidic with a pH less than 7.
(2) The solution is acidic with a pH greater than 7.
(3) The solution is basic with a pH less than 7.
(4) The solution is basic with a pH greater than 7.
What is the color of bromcresol green indicator in a solution with a pH value of 2.0?
(1) blue
(2) green
(3) red
(4) yellow
Which indicator is blue in a solution that has a pH value of 7.0?
(1) bromcresol green
(2) methyl orange
(3) phenolphthalein
(4) thymol blue
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.
What is the color of the indicator thymol blue after it is added to an aqueous solution of vitamin C?
Allow 1 credit for yellow.
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.
State the color of methyl orange indicator after the indicator is placed in the solution.
Allow 1 credit for red.
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)
State the color of bromcresol green in a sample of NH3(aq).
Allow 1 credit for blue.
The pH of various aqueous solutions are shown in the table below.
Complete the table below by writing the color of thymol blue in the NaCl(aq) and in the NaOH(aq) solutions.
Allow 1 credit.
• Example of a 1-credit response:
• chem12015-rg_g3.png
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.
Hydrangea plants can be grown in soil that turns litmus red. What color are the flowers of the plants grown in this soil?
Allow 1 credit for blue.
State the color of methyl orange indicator after the indicator is placed in a solution of 0.10 M NH3(aq).
Allow 1 credit for yellow.
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.
Which labeled part of the digestive system has the most acidic environment?
Allow 1 credit. Acceptable responses include, but are not limited to:
• stomach
• the organ with a pH of 2
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.
What would be the color of bromcresol green if it had been added to the water in the flask before any of the HCl(g) was bubbled through the water?
Allow 1 credit for blue.