a volumetric flask made of pyrex is calibrated at 20°c. if it is filled to 100ml with 35°c acetone.
what us the volume of the acetone when it cools to 20°c and how significant is the change in the volume of the flask.
To calculate the volume of acetone when it cools to 20°C, we need to consider the thermal expansion properties of both the pyrex flask and the acetone. Pyrex has a coefficient of thermal expansion of approximately 3.3 × 10^(-6) per °C, while the coefficient of thermal expansion for acetone is roughly 9.0 × 10^(-4) per °C.
First, let's determine the change in volume of the flask. Since the flask is calibrated at 20°C, there will be no change in its volume at this temperature. Therefore, the change in volume of the flask is zero.
Next, let's calculate the change in volume of the acetone. We need to determine the initial volume of the acetone at 35°C and then calculate its volume at 20°C.
To do this, we'll use the formula:
ΔV = V * α * ΔT
Where:
ΔV is the change in volume
V is the initial volume
α is the coefficient of thermal expansion
ΔT is the change in temperature
Given:
Initial volume of acetone (V) = 100 mL
Coefficient of thermal expansion for acetone (α) = 9.0 × 10^(-4) per °C
Change in temperature (ΔT) = 35°C - 20°C = 15°C
ΔV = (100 mL) * (9.0 × 10^(-4) per °C) * (15°C)
ΔV = 1.35 mL
Therefore, the volume of the acetone when it cools to 20°C is 100 mL - 1.35 mL = 98.65 mL.
The significant change in volume of the flask is zero since the flask doesn't expand or contract at 20°C. However, the change in volume of the acetone is 1.35 mL, which is a significant change when considering a total volume of 100 mL.