Sam Student calibrates a flask with water at 20C. Patricia Pupil borrows the flask and Sam's calculated volume for the flask, and uses it to do her unknown at 25 C. What, if any specific effect will this have on the results of Patricia's density determination? Explain your answer.

My Chem teacher didn't even try to explain how to do this problem. Any help is appreciated. ;)

Look up the density of water at 20C and the density of water at 25C. They are not the same. Knowing that mass = volume x density, then density = mass/volume. The volume you calculate for the flask will be different and that will cause the density of your determination to be different. Plug in the two density numbers and see how that affects the results. Post you thoughts if you need more assistance. A hint:

d@20C = 0.998703 g/cc
d@25C = 0.997044 g/cc
volume of the flask = m/d so the volume Patricia uses will be too low. How will that affect Patricia's density?

Thanks. I think I get it, but I don't know how to get the mass...

To determine the effect on Patricia's density determination, we need to consider the relationship between temperature and density. Density is defined as the mass per unit volume of a substance.

When temperature increases, the volume of most substances also increases. This is because as the temperature rises, the molecules of the substance gain energy and move more vigorously, causing them to take up more space. This increase in volume results in a decrease in density, assuming the mass remains constant.

In this scenario, when Sam calibrated the flask with water at 20°C, he measured the volume of the flask at this temperature. However, when Patricia borrowed the flask and used it to determine the density of an unknown substance at 25°C, the volume of the flask would have expanded due to the increase in temperature.

As we know from above, an increase in temperature results in an increase in volume, which subsequently leads to a decrease in density, assuming the mass remains constant. Therefore, the specific effect on Patricia's density determination is that the calculated density of the unknown substance would be lower than the actual value because the increase in volume would result in a smaller value for density.

To avoid this issue, it is important to either measure the volume of the flask at the same temperature as the experiment or correct for the temperature difference using appropriate formulas or conversion factors.