(a) What is meant by the term fuel value? (b) Which is a greater source of energy as food, \(5 \mathrm{~g}\) of fat or \(9 \mathrm{~g}\) of carbohydrate? (c) The metabolism of glucose produces \(\mathrm{CO}_{2}(g)\) and \(\mathrm{H}_{2} \mathrm{O}(l) .\) How does the human body expel these reaction products?

Short Answer

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(a) Fuel value is the amount of energy released when a substance is consumed and metabolized by an organism, typically expressed in calories or joules per unit mass. (b) 5g of fat provides more energy as food than 9g of carbohydrate (45 cal > 36 cal). (c) The human body expels the reaction products of glucose metabolism (CO2 and H2O) through the respiratory system (CO2 is exhaled) and various processes such as urination, sweating, breath moisture, and fecal excretion (removal of H2O).

Step by step solution

01

a) Definition of fuel value

Fuel value is a measure of the amount of energy that is released when a substance (usually food) is consumed and metabolized by an organism, typically expressed in calories or joules per unit mass. In the context of nutrition, fuel value tells us how much energy a specific food provides for the body to perform various tasks.
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b) Comparing energy content of fat and carbohydrate

To compare the energy content of fat and carbohydrate, we will use their fuel values, which are generally known. Fat has a fuel value of approximately 9 calories per gram (cal/g) while carbohydrate has a fuel value of approximately 4 cal/g. Given the amounts of fat and carbohydrate provided in the problem (5 g of fat and 9 g of carbohydrate), we can calculate the total energy content of each: Energy provided by fat = (Fuel value of fat) x (Amount of fat) = 9 cal/g * 5 g = 45 cal Energy provided by carbohydrate = (Fuel value of carbohydrate) x (Amount of carbohydrate) = 4 cal/g * 9 g = 36 cal Since 45 cal > 36 cal, 5 g of fat provides more energy as food than 9 g of carbohydrate.
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c) Expelling reaction products of glucose metabolism

As mentioned in the question, the metabolism of glucose produces carbon dioxide (CO2) and water (H2O). The human body has evolved a mechanism to expel these reaction products: 1. Carbon dioxide (CO2): The primary method for CO2 removal is through the respiratory system. CO2 produced during cellular metabolism diffuses into the bloodstream, where it combines with water to form carbonic acid. This acid dissociates into bicarbonate ions and hydrogen ions, and the bicarbonate ions are carried along the bloodstream to the lungs. Here, they recombine with hydrogen ions to form carbonic acid, which then breaks down to release CO2 gas. This CO2 gas is expelled from the body through the process of exhalation. 2. Water (H2O): The water produced during glucose metabolism contributes to the body's overall water content. Excess water is removed from the body through various processes, the primary one being urination. Additionally, water is also lost through sweating, breath moisture, and fecal excretion.

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Most popular questions from this chapter

(a) When a 4.25 -g sample of solid ammonium nitrate dissolves in \(60.0 \mathrm{~g}\) of water in a coffee-cup calorimeter (Figure 5.18), the temperature drops from \(22.0^{\circ} \mathrm{C}\) to \(16.9^{\circ} \mathrm{C}\). Calculate \(\Delta H\left(\right.\) in \(\left.\mathrm{kJ} / \mathrm{mol} \mathrm{NH}_{4} \mathrm{NO}_{3}\right)\) for the solution process $$ \mathrm{NH}_{4} \mathrm{NO}_{3}(s) \longrightarrow \mathrm{NH}_{4}^{+}(a q)+\mathrm{NO}_{3}^{-}(a q) $$ Assume that the specific heat of the solution is the same as that of pure water. (b) Is this process endothermic or exothermic?

When a \(6.50-\mathrm{g}\) sample of solid sodium hydroxide dissolves in \(100.0 \mathrm{~g}\) of water in a coffee-cup calorimeter (Figure 5.18 ), the temperature rises from \(21.6^{\circ} \mathrm{C}\) to \(37.8^{\circ} \mathrm{C}\). Calculate \(\Delta H\) (in \(\mathrm{kJ} / \mathrm{mol} \mathrm{NaOH})\) for the solution process $$ \mathrm{NaOH}(s) \longrightarrow \mathrm{Na}^{+}(a q)+\mathrm{OH}^{-}(a q) $$ Assume that the specific heat of the solution is the same as that of pure water.

(a) Why are fats well suited for energy storage in the human body? (b) A particular chip snack food is composed of \(12 \%\) protein, \(14 \%\) fat, and the rest carbohydrate. What percentage of the calorie content of this food is fat? (c) How many grams of protein provide the same fuel value as \(25 \mathrm{~g}\) of fat?

Consider two solutions, the first being \(50.0 \mathrm{~mL}\) of \(1.00 \mathrm{M} \mathrm{CuSO}_{4}\) and the second \(50.0 \mathrm{~mL}\) of \(2.00 \mathrm{MKOH}\). When the two solutions are mixed in a constant-pressure calorimeter, a precipitate forms and the temperature of the mixture rises from \(21.5^{\circ} \mathrm{C}\) to \(27.7^{\circ} \mathrm{C}\). (a) Before mixing, how many grams of Cu are present in the solution of \(\mathrm{CuSO}_{4} ?\) (b) Predict the identity of the precipitate in the reaction. (c) Write complete and net ionic equations for the reaction that occurs when the two solutions are mixed. (d) From the calorimetric data, calculate \(\Delta H\) for the reaction that occurs on mixing. Assume that the calorimeter absorbs only a negligible quantity of heat, that the total volume of the solution is 100.0 \(\mathrm{mL},\) and that the specific heat and density of the solution after mixing are the same as that of pure water.

Using values from Appendix \(\mathrm{C},\) calculate the value of \(\Delta H^{\circ}\) for each of the following reactions: (a) \(\mathrm{CaO}(s)+2 \mathrm{HCl}(g) \longrightarrow \mathrm{CaCl}_{2}(s)+\mathrm{H}_{2} \mathrm{O}(g)\) (b) \(4 \mathrm{FeO}(s)+\mathrm{O}_{2}(g) \longrightarrow 2 \mathrm{Fe}_{2} \mathrm{O}_{3}(s)\) (c) \(2 \mathrm{CuO}(s)+\mathrm{NO}(g) \longrightarrow \mathrm{Cu}_{2} \mathrm{O}(s)+\mathrm{NO}_{2}(g)\) (d) \(4 \mathrm{NH}_{3}(g)+\mathrm{O}_{2}(g) \longrightarrow 2 \mathrm{~N}_{2} \mathrm{H}_{4}(g)+2 \mathrm{H}_{2} \mathrm{O}(l)\)

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