A system performs 111 kJ of work on its surroundings and releases 89 kJ of heat. What is the value of ΔE (in kJ) for the system?

A system releases 43 kJ of heat and has 94 kJ of work done on it. What is the value of ΔE (in kJ) for the system?

Of the following, the heat of formation,  ΔH°f, is zero for              .  

Consider the reaction of iron (III) oxide with carbon to form iron metal and carbon dioxide gas: 2 Fe2O3 (s) + 3 C (c) →  4 Fe (s) +  3 CO2 (g)            

Based on the activity series, which of the following solutions would result in a spontaneous single displacement reaction with lead metal?

Consider the reaction where hydrogen gas reacts with bromine gas to form hydrogen bromide gas: H2 (g) + Br2 (g) →  2 HBr (g)      

What is the oxidation number for the chlorine atom in the compound, potassium perchlorate, KClO4?

46 mL of water is added to 204 mL of 7.0 M AgNO3 What is the concentration, in M, of the resulting solution? Hint:  Vwater = V2 (final volume) – V1 (initial volume)

Consider the reaction below: CH4 (g) + 2 O2 (g) → CO2 (g) + 2 H2O (g) The element                   is undergoing oxidation and                     is the oxidizing agent.

Copper (II) hydroxide is formed in the following reaction: CuSO4 (aq) + 2 NaOH(aq) →  Cu(OH)₂ (s) +  Na2SO4 (aq)  How much copper(II) hydroxide precipitate (in g) is formed when 25.0 mL of 0.612 M NaOH reacts with an excess of CuSO4?   Hint: Molar mass for Cu(OH)2 is 97.57 g/mol