Reaction Quotient Calculator
⚖ Acids, Bases & Equilibrium. Use the Reaction quotient formula to find qc, [a], a, [b], b, [c], c, [d], d: pick the value you want, type the others, and the answer updates as you go.
Compare with K: Q < K → goes forward, Q > K → goes back, Q = K → at equilibrium.
Pick the ○ next to the value you want to find, fill in the others, and it solves as you type.
What each letter means
| Quantity | Unit |
|---|---|
| Qc | no unit |
| [A] | mol/L |
| a | no unit |
| [B] | mol/L |
| b | no unit |
| [C] | mol/L |
| c | no unit |
| [D] | mol/L |
| d | no unit |
Worked example
Find the qc when [A] = 0.5 mol/L, a = 1, [B] = 1.5 mol/L, b = 3, [C] = 1.2 mol/L, c = 2, [D] = 1 mol/L, d = 0.
Using Qc = [C]t^c[D]t^d/[A]t^a[B]t^b: Qc = 0.85333.
Frequently asked questions
What is the formula for Reaction quotient?
Qc = [C]t^c[D]t^d/[A]t^a[B]t^b. Compare with K: Q < K → goes forward, Q > K → goes back, Q = K → at equilibrium.
What do the letters stand for, and what units are used?
Qc, [A] in mol/L, a, [B] in mol/L, b, [C] in mol/L, c, [D] in mol/L, d.
How do you calculate qc?
Put the values into Qc = [C]t^c[D]t^d/[A]t^a[B]t^b. For example, with [A] = 0.5 mol/L, a = 1, [B] = 1.5 mol/L, b = 3, [C] = 1.2 mol/L, c = 2, [D] = 1 mol/L, d = 0, qc = 0.85333.
Can I solve for a different value?
Yes. In the calculator above, pick the circle next to any value (qc, [a], a, [b], b, [c], c, [d], d) and fill in the others: it rearranges the formula for you.
