chemistry homework on acids bases and buffers
Below I attached the questions and also connected the docx version as well. Thank you!
- Consider the following substances: CH5N, C2H5O2COOH, H3AsO4, KClO2, HC2H2ClO2. For each compound
- Decide whether the compound behaves as an acid or base in solution
- Write the equation for the dissociation of the compound in water
- Write the equilibrium expression for the dissociation in water
- Calculate the [H+], the [OH–], the pH and the pOH for a solution prepared by diluting 50.0 ml of 0.035 M HNO3 to 250 ml in a volumetric flask.
- Fluoroacetic acid, C2H3FO2, occurs naturally in at least 40 plants found in Australia, Brazil and in Africa, notably in “Gifblaar†which is one of the most poisonous plants found in South Africa. The compound is highly toxic and causes convulsions and ventricular fibrillation and has been used to poison rats. If the Ka of this acid is 2.57 x 10-3 determine the [H+], the [OH–], the pH and the pOH for a 0.05 M solution of this acid.
- Strontium hydroxide is used in refining beet sugar and separating cyrstallizable sugar from molasses.It is commonly found as the octahydrate, Sr(OH)2.8H2O. If a solution is prepared by dissolving 0.45 grams of this compound in sufficient water to make 100 ml of solution, determine the [H+], the [OH–], the pH and the pOH of the solution.
- Ethylamine (C2H5NH2) is a flammable liquid with an ammonia-like odor that is miscible with water. It is irritating to skin, mucous membranes and to the respiratory tract. The density of ethylamine is 0.689 g/ml. If the Ka of this compound is 2 x 10-11, determine the [H+], the [OH–], the pH and the pOH of a solution prepared by dissolving 25.0 ml of this compound in 500 ml of solution.
- Phenylpropionic acid, C9H10O2, also known as hydrocinnamic acid , is a white crystalline solid with a sweet floral scent at room temperature. It has a wide variety of uses including cosmetics, food additives, and pharmaceuticals. If a 0.075 M solution of this acid has a pH of 2.89, determine the Ka for the acid.
- Ethanolamine, C2H7NO, is a clear, viscous, hygroscopic liquid with an ammonia-like odor. It is used to remove CO2 and H2S from natural gas but it is also found in polishes, hair waving solutions, and in emulsifiers (often in pharmaceuticals). Overexposure to this compound can cause irritation to the eyes, skin and respiratory system as well as lethargy. If a 0.25M solution of this compound is found to be 1.125 % ionized, determine the Kb and the Ka for this substance.
- Calculate the pH of a solution made by dissolving 2.5 grams of sodium nitrite (NaNO2) into 150 ml of0.092 M solution of nitrous acid if the Ka of nitrous acid is 4.0 x 10-4.
- All parts of the hemlock plant contain the alkaloid coniine. Coniine (C8H17N) is an alkaline liquid with a pKb of 3.1 and a density of 0.844 g/ml. Ingestion of the substance may cause weakness, drowsiness, nausea, vomiting, labored respiration, paralysis and death. If an attempted murderer poured 2.5 ml of coniine into someone’s 500 ml water bottle, what would the pH be for the resulting solution?If the lethal dose for mice of 7 mg/kg of body weight is similar to that for humans, would a 120 pound athlete die from drinking the contents of the water bottle?
- Lactic acid, HC3H5O3, is a substance found in sour milk products such as yogurt, and is produced naturally by fermentation in body cells during normal metabolism and exercise The Ka for lactic acid is 1.38 x 10-4. Its sodium salt, sodium lactate, NaC3H5O3, is used in foods as a preservative and acidity regulator. It is also used in shampoo products as an effective humectant and moisturizer. Determine the pH of a solution prepared by adding 4.5 grams of sodium lactate and 2.0 grams of lactic acid to 500 ml of total solution.
- What is the new pH of a solution if 5.0 ml of 0.10 M HBr is added to 200 ml of a buffer system that is 0.10 M Benzoic acid and 0.10 M sodium benzoate.(The Ka of benzoic acid is 6.3 x 10-5)
- Propionic acid, C2H5COOH, is an oily liquid that has a slightly pungent, disagreeable rancid odor. It is found in dairy products in small amounts. Its sodium salt, sodium propionate, C2H5COONa, has wide application as a food preservative, fungicide and mold inhibitor. What is the ratio of propionic acid to sodium propionate in a buffer solution that has a pH of 4.26, if the Ka of propionic acid is 1.38 x 10-5? If exactly 1.0 liters of the buffer solution is to be prepared, how many grams of C2H5COONa will be required?
- Hydrogen cyanide (HCN), sometimes called prussic acid, is a colorless, extremely poisonous and flammable liquid that boils slightly above room temperature (25.6 °C).HCN is produced on an industrial scale and is a highly valuable precursor to many chemical compounds ranging from polymers to pharmaceuticals Determine the pH of a buffer solution is prepared by mixing 125 ml of 0.080 M KCN with 200 ml of 0.025 M HCN. The Ka of HCN is 6.2 x 10-10
- Determine the pH of a solution prepared by diluting 50.0 ml of bleach, a 4% w/V solution of NaClO (sodium hypochlorite), to a new volume of 250 ml, if the Ka of HClO is 3 x 10-8.
16. Exactly 25.00 ml of 0.0685 M HClO4 solution is placed in a flask and titrated with standardized 0.050M NaOH.
A. Determine the endpoint of the titration
B. Determine the pH of the solution after the following amounts of NaOH are added to the acid solution:
a.) Initially, 0.00 ml NaOH.b.) 5.00 ml c.) 15.00 ml
d.) 25.00 ml e.) 34.00 ml f.) At the endpoint of the titration
g.) 34.35 ml h.) 45.00 ml i.) 50.00 ml
17. Exactly 25.00 ml of a 0.0685 M pentanoic acid solution,(C4H8O2), is placed in a flask and titrated with standardized 0.050 M NaOH.(the pKa of this acid is 4.84).
A. Determine the endpoint of the titration
B. Determine the pH of the solution after the following amounts of NaOH are added to the acid solution:
a.) Initially, 0.00 ml NaOH.b.) 5.00 ml c.) 15.00 ml
d.) 25.00 ml e.) 34.00 ml f.) At the endpoint of the titration
g.) 34.35 ml h.) 45.00 ml i.) 50.00 ml
18. Make a labeled rough sketch of pH vs. ml of NaOH for the titrations performed in questions #16 and #17
