# Finding the Amount of Water in a Solution

Purpose: The intent of this lab is to find the percent of water in blue stuff.

Procedure:
1. Place the blue stuff in a 150 ml beaker.
2. Heat the blue stuff with a Bunsen burner
3. Make successive weightings between heatings of blue stuff until there is less than .02g difference between the current and previous weights. Make sure to record all measurements.

 Measurements: Mass of test tube (g) 13.46 Mass of test tube and blue compound before heating (g) 14.30 Mass of blue compound (g) 0.84 Mass of test tube and compound after heating (g) 14.05 Mass of blue compound after first heating (g) 0.59 Mass of blue compound after second heating (g) 0.54 Mass of blue compound after third heating (g) 0.54 Mass of water that left blue compound (g) 0.25 % of water in compound (%) 30 Accepted amount of water in blue stuff (g) 36 % Error (%) 16

Calculations:

Mass of compound(g) = Mass of test tube and compound(g) - Mass of test tube(g) = 14.30g - 13.46g = 0.84g

Mass of water evaporated(g)=Mass of compound(g) - Mass of compound after heating(g)=0.84g - 0.59g= 0.25g

% of water in compound = Mass of water in compound    x   100%    =    0.25     x   100%  =  30%
Mass of compound                                   0.84

% Error = Measured - Accepted   x 100% = 30 - 36 x 100% = 6  x 100% = 0.16 x 100% = 16%
Accepted                                 36                    36

Error Analysis: During the heating of the blue compound it was observed that excessive exposure to heat caused the blue compound (white after heating) to turn a yellow hew. This indicates burning which will produce additional chemical changes in the blue compound and may vaporize additional elements.