20. Heat and Temperature

(II) An aluminum sphere is 8.75 cm in diameter. What will be its % change in volume if it is heated from 30°C to 140°C?

(II) The density of water at 4°C is 1.00 x 10³ kg / m³ . What is water’s density at 94°C? Assume a constant coefficient of volume expansion.

A Pyrex measuring cup was calibrated at normal room temperature. How much error will be made in a recipe calling for 375 mL of cool water, if the water and the cup are hot, at 95°C, instead of at room temperature? Neglect the glass expansion.

The density of gasoline at 0°C is 0.68 x 10³ kg/m³ .

(a) What is the density on a hot day, when the temperature is 33°C?

(b) What is the percent change in density?

(II) It is observed that 55.50 mL of water at 20°C completely fills a container to the brim. When the container and the water are heated to 60°C, 0.35 g of water is lost.

(a) What is the coefficient of volume expansion of the container?

(b) What is the most likely material of the container? Density of water at 60°C is 0.98324 g/mL .

(II) A glass is filled to the brim with 450.0 mL of water, all at 100.0°C. If the temperature of glass and water is decreased to 20.0°C, how much water could be added to the glass?

(III) Water’s coefficient of volume expansion in the temperature range from 0°C to about 20°C is given approximately by β = α + bT + cT² , with α = - 6.43 x 10⁻⁵ (C°)⁻¹ , b = 1.70 x 10⁻⁵ (C°)⁻² , and c = -2.02 x 10⁻⁷ ((C°)⁻³ . Using the formula for density from Problem 22, show that water has its greatest density at approximately 4.0°C.

(II) At a given latitude, ocean water in the so-called mixed layer (from the surface to a depth of about 50 m) is at approximately the same temperature due to the mixing action of waves. Assume that because of global warming, the temperature of the mixed layer is everywhere increased by 0.5°C, while the temperature of the deeper portions of the ocean remains unchanged. Estimate the resulting rise in sea level. The ocean covers about 70% of the Earth’s surface.

(II) In an alcohol-in-glass thermometer, the alcohol column has length 12.61 cm at 0.0°C and length 22.79 cm at 100.0°C. What is the temperature if the column has length

(b) 14.40 cm?

(II) A uniform rectangular plate of length ℓ and width ω has a coefficient of linear expansion α.

(a) Show that, if we neglect very small quantities, the change in area of the plate due to a temperature change ∆T is ∆A = 2αℓω ∆T . See Fig. 17–21.

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"(II) Wine bottles are never completely filled: a small volume of air is left in the glass bottle’s cylindrically shaped neck ( inner diameter d = 18.5 mm) to allow for wine’s fairly large coefficient of thermal expansion. The distance H between the surface of the liquid contents and the bottom of the cork is called the “headspace height” (Fig. 17–22), and is typically H = 1.5 cm for a 750-mL bottle filled at 20°C. Due to its alcoholic content, wine’s coefficient of volume expansion is about double that of water; in comparison, the thermal expansion of glass can be neglected. Estimate H if the bottle is kept

(a) at 10°C

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Estimate the percent difference in the density of iron at STP, and when it is a solid deep in the Earth where the temperature is 2000°C and under 5000 atm of pressure. Assume the bulk modulus ( 90 x 10⁹ N/m² ) and the coefficient of volume expansion do not vary with temperature and are the same as at STP.

(II) Consider three capacitors, of capacitance 3100 pF, 5800 pF, and 0.0100 μF . What maximum and minimum capacitance can you form from these? How do you make the connection in each case?

(a) The tube of a mercury thermometer has an inside diameter of 0.140 mm. The bulb has a volume of 0.285 cm³. How far will the thread of mercury move when the temperature changes from 10.5°C to 33.0°C? Take into account expansion of the Pyrex glass.