help with equilibrium questions!

[rinner]

hey, I was just wondering if someone could explain how to get the textbook answers for these equilibrium questions.

11) An equilibrium mixture contains 0.020 mol of H2O gas, 0.030 mol H2 gas, 0.040 mol CO gas and
0.050 mol of CO2 gas in a 2.0 L container. The gases react according to the equation:
\(\ce{H2(g) + CO2(g) <=> H2O(g) + CO(g)}\)
Calculate the equilibrium constant at 900°C.

The answer is 0.53 but I got 5.3 X 10 to the power of -9
also

12)At a specified temperature the reaction between solutions of Sn2+ and Fe3+ reaches equilibrium
according to the equation: \(\ce{2Fe^3+(aq) + Sn^2+(aq) <=> 2Fe^2+(aq) + Sn^4+(aq)}\)
The equilibrium concentrations are 0.30 M Fe3+, 0.40 M Fe2+, 0.20 M Sn4+ and 0.10 M Sn2+.
Calculate the equilibrium constant at this temperature with the correct units.

The answer I got is 3.6 x 10 to the power of -6, but the answer is 3.6
Thanks in advance!!

[TheBigC]

hey, I was just wondering if someone could explain how to get the textbook answers for these equilibrium questions.The answer is 0.53 but I got 5.3 X 10 to the power of -9
also The answer I got is 3.6 x 10 to the power of -6, but the answer is 3.6
Thanks in advance!!

11) ((0.020/2.0)*(0.040/2.0))/((0.050/2.0)*(0.030/2.0)) = 0.53
12) ((0.4)^2*(0.2))/((0.3)^2*(0.1)) = 3.6

The method by which one calculates the equilibrium constant is:

Let a reaction be represented by aA + bB --> cC + dD,

Keq (at specific temperature) = ((concentration of C)^c*(concentration of D)^d)/((concentration of A)^a*(concentration of B)^b)

[sweetcheeks]

Can you post how you have tried to solve these questions? It would make it a lot easier to see where you may have gone wrong.

[rinner]

thank you TheBigC!!
I realised my calculator was automatically converting the values to scientific values, so when I divided them it ended up multiplying the negative indices rather than dividing them.