Question

Scurrilous con artists have been known to represent gold-plated tungsten ingots as pure gold and sell them at prices much below gold value but deservedly far above the cost of tungsten. With what accuracy must you be able to measure the mass of such an ingot in and out of water to tell that it is almost pure tungsten rather than pure gold?

A. 0.1%
B. 0.5%
C. 1.0%
D. 2.0%

Answer 1

To determine if an ingot is pure gold or gold-plated tungsten, you can measure the mass of the ingot in and out of water. To distinguish between the two, you need to measure the mass with an accuracy of at least 1.0%.

Step-by-step explanation:

In order to differentiate between a gold-plated tungsten ingot and a pure gold ingot, we can use the concept of buoyancy. The difference in densities of gold and tungsten allows us to determine their purity by measuring the mass of the ingot both in and out of water.

If we assume that the ingot is made entirely of pure gold or pure tungsten, we can calculate the expected change in mass when it is submerged in water. The equation we can use is:

Δm = (density of fluid)(volume of displaced fluid)

If the measured change in mass is significantly different from the expected change based on the density of gold, we can conclude that the ingot is not pure gold, but rather mostly tungsten. To have a clear distinction between the two, we need to measure the mass with an accuracy of at least 1.0%.