## Estimate f, and find the uncertainty in the estimate.

1.  The lens equation says that if an object is placed at a distance p from a lens, and an image is formed at a distance q from the lens, then the focal length f satisfies the equation 1/f = 1/p + 1/q. Assume that p = 2.3 ± 0.2 cm and q = 3.1 ± 0.2 cm.

a.  Estimate f, and find the uncertainty in the estimate.

b.  Which would provide a greater reduction in the uncertainty in f: reducing the uncertainty in p to 0.1 cm or reducing the uncertainty in q to 0.1 cm?

2.    The pressure P, temperature T, and volume V of one mole of an ideal gas are related by the equation PV = 8.31 T, when P is measured in kilopascals, T is measured in kelvins, and V is measured in liters.

a.   Assume that P = 242.52 ± 0.03 kPa and V = 10.103 ± 0.002 L. Estimate T, and find the uncertainty in the estimate.

b.  Assume that P = 242.52 ± 0.03 kPa and T = 290.11 ± 0.02 K. Estimate V, and find the uncertainty in the estimate.

c.    Assume that V = 10.103 ± 0.002 L and T = 290.11 ± 0.02 K. Estimate P, and find the uncertainty in the estimate.

### Determine the outlet concentration x1 in the water solution and in the trichloroethane solution using an analytical equation.

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### Calculate the minimum solvent that can be used. [Hint: In this case, the tie line through the feed L0 represents the condition for minimum solvent flow rate.

Minimum Solvent and Countercurrent Extraction of Acetone. An aqueous feed solution of 1000 kg/h containing 23.5 wt % acetone and 76.5 wt % water is being extracted in a countercurrent….

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