Thanks in advance!!! temperature of 140°C. If the final temperature reached by t

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Thanks in advance!!! temperature of 140°C. If the final temperature reached by the copper-water mixture is 36.0 °C, how many grams of water are present? 71 A 25.0-g sample of a metal at 98.0 °C is placed in 500 g of water at 18.0 °C. If the final temperature of the alloy and water is 27.4 °C, what is the specific heat of the metal? 72 A 0.50-g sample of vegetable oil is placed in a calorimeter When the sample is burned, 18.9 kJ is given off. What is the energy value (kcal/g) of the oil? 77 A typical detin the United States provides 15% of the calories from protein, 45% from carbohydrates, and the remainder from fats. Calculate the grams of protein, carbohydrate, and fat to be included each day in diets having the following calorie requirements: a. 1200 kcal b. 1900 kcal c. 2600 kcal A 125-g piece of metal is heated to 288 °C and dropped into 85.0 g of water at 26 °C. If the final temperature of the water and metal is 58.0 °C, what is the specific heat of the metal (J/g °C)? Rearrange the heat equation to solve for each of the following: a. the mass, in grams, of water that absorbs 8250 J when its 78 79 temperature rises from 18.3 °C to 92.6 °C b. the mass, in grams, of a gold sample that absorbs 225 J when the temperature rises from 15.0 °C to 47.0 °C c. the rise in temperature when a 20.0-g sample of iron absorhs

Explanation / Answer

73)

m= 0.66 g of oil

mw = 370 g

Tf = 38.8

Ti = 22.7

Then

Heat content kJ/g and kcal/g

First, find the heat

Q = m*Cp*(Tf-Ti)

Q = 370*4.184*(38.8-22.7) = 24924.088 J = 24.9 kJ

Q = 370*1*(38.8-22.7) = 5957 cal = 5.957 kcal

Then per unit mass

Hrxn = 24.9 /0.66 = 37.727 kJ/g

Hrxn = 5.957  /0.66 = 9.025 kcal/g

75)

cp = 0.385 J/gC

T = 86

m = 50 g water

T = 16 °c

Tf = 24

mass of copeer?

Qwater = -Qcupper

Qwater= 50*4.184*(24-16) = 1673.6

Then

Qcop = m*0.385*(86-24)

-1673.6 = m*0.385*(86-24)

m = 673.6/(0.385*(86-24))= 70.1131 g of copper

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