Question

A precipitation reaction is caused by mixing 100. mL of 0.25 M K2Cr2O7 solution with 100. mL of 0.25 M Pb(NO3)2 solution. When the precipitate forms, it is filtered from the mixture.Which describes the changes in concentration of the spectator ions K+ and NO3- in the reaction mixture as the reaction occurs?K+ is doubled, NO3- halvedNeither is affectedK+ is halved, NO3- halvedBoth are doubled

Answer 1

Answer:

Neither is affected

Explanation:

The reaction occurs as follows:

K₂Cr₂O₇ + Pb(NO₃)₂ → PbCr₂O₇ + 2K⁺ + 2NO₃⁻

That means per mole of reaction you will have two moles of both K⁺ and NO₃⁻.

But volume is also doubled, doing that concentration of spectator ions doesn't change.

Right answer: Neither is affected

I hope it helps!