A seed of CuSO4.5H20 with a mass of 0.500 g was carefully placed into a saturated solution of copper (II) sulfate. After 7 days the mass of the seed crystal was determined to be 0.648 g. After 14 days the mass of the crystal increased to 0.899 g and after 21 days the mass of the crystal was found to be 1.081 g. Make a plot of mass vs time (days) and extrapolate to predict what would be the mass of the crystal in 28 days if the growth is linear. Include labels and units on each axis.

mass of the gram after 28 days = 1.29 grams

Explanation:

From the diagram attached below; we would see the plot of the mass vs the time (days).

However ; to predict what would be the mass of the crystal after 28 days  if the growth is linear; we have the following analysis;

Let the mass be Y ( since it falls on the y-axis) and the time (days) be X (since it falls on the x-axis)

So; we can have a table as shown below:

              X                 Y                   XY                   XX

              0                  0.500          0                       0

              7                   0.648          4.536               49

              14                 0.899           12.586            196

              21                  1.081            22.701            441

Total   :42                3.128            39.823         686

If the growth is linear ; the linear regression equation can be represented as :

y = a+ bx

where ;

and

n = samples given =  4

x = number of days = 28

so;

from the table ; replacing the corresponding values; we have:

a = 0.4829

b = 0.0289

Recall:

y = a+ bx

y = 0.4829 + 0.0289 (28)

y = 0.4829 + 0.8092

y = 1.2921 grams

y ≅ 1.29 grams

mass of the gram after 28 days = 1.29 grams

there are two significant figures.