1. LAB#4 MOLE RATIOS, QUALATATIVE
The coefficient of each substance is the ratio that exists between it and the coefficients of each of the other substance in the reaction.
The mole is the universal unit of chemical ratio, it applies to all compounds, elements and phases .
In this reaction, any substance that has no coefficient in front of it is assumed to have a coefficient of 1 (as in algebra). The KNO3 has a coefficient of 2.
Pb(NO3)2(aq) + K2Cr2O7(aq)  PbCr2O7(s)) + 2 KNO3(aq)

2. EXPERIMENTAL DESIGN
IN THIS LAB, THE REACTANTS (REAGENTS) ARE SUPPLIED AS AQUEOUS SOLUTIONS (aq). Each solution has the same concentration, the same number of particles are present in the same volume of each solution.
Because each solution has the same concentration, equal volumes have equal number of particles: volume ratios are mole ratios.
The volume ratio (which is the mole ratio) that gives you the most solid product (height in well) is the real mole ratio. You ARE TRYING TO PROVE EXPERIMENTALLY WHAT IS KNOWN THEORETICALLY IN THE BALANCED REACTION GIVEN.
Use your imagination to diagram the reaction, this is called a simulation or model (File number 5 on school web -download it).