Chemistry Answers

Aqueous solutions of potassium hydrogen sulfate and potassium hydroxide react to form aqueous potassium sulfate and liquid water. How many moles of potassium hydroxide are necessary to form 0.636 moles of potassium sulfate?

A quantity of NaOH of mass 1.1g is dissolved in water and made up to 250cm³ in a graduated flask. A 20cm³ of the solution neutralizes 20.4cm³ of a solution of acetic acid of ph=2.85

Calculate

a. Number of moles of NaOH in the 250cm³ solution

b. Number of moles of acetic acid in 1dm³ of the solution

State the volume of hydrogen gas produced at s.t.p when using 30g of Zinc is added to excess dilute hydrochloric acid at 33⁰C and pressure ( H= 1, Zn =65, Cl = 35.5 ) molar mass of gas ay s.t.p = 22.4dm³

The reaction goes to completion, but in the process of washing and drying the precipitate, some was lost. The percent yield for the reaction is 79.9%

79.9%. How many grams of precipitate are recovered?

precipitate recovered:

How many grams of the excess reactant remain? Assume the reaction goes to completion.

excess reactant remaining:

The reaction goes to completion, but in the process of recovering the product, some of it was lost. The the percent yield for the reaction is 82.2%.

82.2%. How many grams of product are recovered?

mass of product recovered:

How many grams of the excess reactant remain? Assume the reaction goes to completion.

mass of excess reactant:

Consider the following equation:

Ca(OH)2(s) + 2 HCl(aq) —> CaCl2(aq) + 2 H2O(l)

a) How many liters of 0.100 M HCl is required to completely react with 5.00 grams of calcium hydroxide?

b) If 15.0 grams of calcium hydroxide is combined with 75.0 mL of 0.500 M HCl, how many grams of calcium chloride

would be formed?

A solution is prepared by mixing 1.00 gram of ethanol (C2H6O) with 100.0 gram water to give a final volume of 101 mL.

Calculate the mole fraction for the solute and solvent, and the molality of ethanol in the solution

Visualize a substance with the following points on the phase diagram: a triple point at 0.5 atm and 150 K; a normal melting point at 175 K; a normal boiling point at 350 K; and a critical point at 2.0 atm and 450 K. The solid liquid line is “normal” (meaning positive sloping). For this, complete the following:

a) Roughly sketch the phase diagram, using units of atmosphere and Kelvin. Label the area 1, 2, and 3, and points T and C on the diagram.

b) Describe what one would see at pressures and temperatures above 2.0 atm and 450 K.

c) Describe the phase changes from 50 K to 250 K at 1.5 atm.

d) What exists in a system that is at 1 atm and 350 K?

e) What exists in a system that is at 1 atm and 175 K?

In the commercial preparation of Hydrogen Chloride, what weight of HCl in grams may be obtained by heating 468 grams of NaCl with H2S04.

2NaCl + H2S04 􏰀 NaSO4 + 2HCl

To make a solution, 40 g of a nonelectrolyte is dissolved into 300 g of water. The freezing point depression of the solution is measured to be -7°C. Calculate the molar mass of the solute.