Chemistry Answers

The standard reaction enthalpy for the docomposition of CaCl₂.NH₃(s) into CaCl₂(s) and NH₃(g) is nearly constant at +78kJmol^-1 between 350 K and 470 K. The equilibrium pressure of NH₃ in the presence of CaCl₂.NH₃ is 1.71kPa at 400K. Find an expression for the temperature dependence of change in Gibbs free energy in the same range

What is the pH of an aqueous solution of 3.99×10^-2 M nitric acid? 

pH = 

2NOBr(g) 2NO(g) + Br₂(g) 

If 0.364 moles of NOBr(g), 0.448 moles of NO, and 0.543 moles of Br₂ are at equilibrium in a 19.1 L container at 464 K, the value of the equilibrium constant, K_c, is  .

An aqueous solution is made by dissolving 29.4 grams of nickel(II) nitrate in 403 grams of water.  

The molality of nickel(II) nitrate in the solution is m

An aqueous solution of sodium bromide, NaBr, contains 3.40 grams of sodium bromide and 17.4 grams of water.

The percentage by mass of sodium bromide in the solution is   %.

The equilibrium mixture is found to contain 0.07, 0.11,0.03 and 0.03 moles of CO ,H2, CH4, H2O respectively for the reaction:

CO(g)+3H2(g)0. CH4=H2O(g)

You need to make an aqueous solution of 0.140 M potassium nitrate for an experiment in lab, using a 125 mL volumetric flask.

How much solid potassium nitrate should you add?

blank grams

In the laboratory you dissolve 18.5 g of nickel(II) bromide in a volumetric flask and add water to a total volume of 125 . mL.  

What is the molarity of the solution?    M

What is the pH of the solution containing 0.20 M NH3 and 0.15 M NH4Cl?

Calculate the pH of a buffer made from 0.28 M HNO2 and 0.23 M NO2-. The Ka for HNO2 is 4.6×10-4