Question

Say the equation of your standard curve graph was y = 0.91x. Your graph shows known sucrose concentrations on your x-axis and their corresponding absorbance values on the y-axis. You want to know how much sucrose concentration is present in your red solution that you measure has an absorbance of 0.64. What is your calculated sucrose concentration? OOOO 0.711 Answer is not listed here

Answer 1

This a problem where you draw a standard curve using increasing concentrations of sucrose on the x-axis and their respective absorbances on the y axis. The curve is a straight line that has equal number of points on each side (best fit) and all the points on each side are collectively equidistant from the line (meaning the total deviations on one side of the line is equal to that on the other side). The line may go through the zero or through the y axis. This line has a slope 'm' and a y-intercept 'c' (the point through which the line cuts the y axis).

These go into the formula: y = mx + c

Here m and c remain constant. The more number of points we use, the more accurate is the curve and hence the equation.

We can now use this equation to find the concentration of any sucrose solution as long as we know its absorbance.

Here the equation is y = 0.91x

c = 0 which means the line goes through the zero.

We have the absorbance which is 0.64. (absorbance is a ratio so it doesn't have units)

So y = 0.64

x = y/0.91

x = 0.64/0.91

x = 0.7033

So the answer is Answer is not listed here.

Note that 0.64/0.90 = 0.711 but that is not the correct answer.