## Chem – Calculating Δ n (Delta n) Part 3

Example: What is the Δ n (delta n) of the equation below?

N2(g) + 3 H2(g) <—-> 2 NH3(g)

Answer: Δ n = 2 – 4 = -2

What is the Δn (delta n) of the equation below?

H2SO4(aq) <—–> H2(aq) + S(s) + 2 O2(aq)

Add together all of the coefficients of the products that involve (aq) or (g) phases.

Answer: 1 H2 + 2 O2 = 3. (S is not counted because it is solid phase)

Add together all of the coefficients of the reactants that involve aq or g phases.

Take the sum of the products minus the sum of the reactants.

Answer: 3 – 1 = 2

What is the Δn (delta n) of the equation below?  GIVE A NEGATIVE ANSWER

PRACTICE PROBLEMS: solve for the Δ n (delta n) in each problem.

What is the Δ n of the equation below?

MgBr2(aq) + 2 NaI(aq) <——> MgI2(aq) + 2 NaBr(aq)

Answer: 3 – 3 = Zero

What is the Δ n of the equation below?

2 H2O(g) <—-> 2 H2(g) + O2(g)

Answer: 3 – 2 = 1

What is the Δ n of the equation below?

2 Fe3+(aq) + 3 CO32-(aq) <—-> Fe2(CO3)3(s)

Answer: 0 – 5 = -5 don’t count Fe2(CO3)3

What is the Δ n of the equation below?

C4(s) + 4 O2(g) <—-> 4 CO2(g)

Answer: 4 – 4 = Zero don’t count C4  