General Chemistry Answers

When copper is heated with an excess of sulfur, copper(I) sulfide is formed. In a given experiment, 1.50 g of copper was heated with excess sulfur to yield 1.53 g copper(I) sulfide. What is the percent yield?

A 37.4 mL sample of H₂ at STP would contain how many grams of hydrogen?

When solid barium hydroxide is mixed in a beaker with solid ammonium thiocyanate, a reaction occurs. The breaker get very cold. Is the reaction endothermic or exothermic?

What weight of NaCl in 800g acetone is needed to bring boiling point to 60°C? (Boiling

point of pure acetone= 55.95°C ; Kb of acetone = 1.71 °C/m)

Calculate the molarity of a sucrose solution made by dissolving 22.61 grams sucrose into water given 969.4 mL of solution. 

Assuming equal concentrations, arrange these solutions by pH. Highest Ph to lowest Ph.

Ca(OH)2(aq) NH3(aq) HCN(aq) LiOH(aq) HCl(aq)

Enough of a monoprotic weak acid is dissolved in water to produce a 0.0133 M solution. The pH of the resulting solution is 2.38. Calculate the K_a for the acid.

Write the balanced equation for the ionization of the weak base pyridine, C5H5N, in water,H2O. Phases are optional.

Using chemical equations, show how the triprotic acid H3PO4 ionizes in water. Phases are optional.

𝐾a1:

𝐾a2:

𝐾a3:

For the diprotic weak acid H₂A, 𝐾a1=3.6×10^−6 and 𝐾a2=6.2×10^−9

What is the pH of a 0.0700 M solution of H2A? 

pH=

What are the equilibrium concentrations of H2A and A2− in this solution?

[H2A]=

[A^2−]=