A marshmallow is burned in a soda can calorimeter and heats up .255 kg of water by 12. 9°C the calorimeter was calibrated and had an calorimetry constant of 8.50 kcal/kg°c. given that carbohydrates contain for kcal/g calculate the mass in grams of the sugar contained in the marshmallow assume that the marshmallow contains no fat or protein

A marshmallow is burned in a soda can calorimeter heating .255kg of water by 12.9 °C. We can calculate the heat absorbed (Qa) by the calorimeter using the following expression.

[tex]Qa = c \times m \times \Delta T = \frac{8.50kcal}{kg.\° C } \times 0.255kg \times 12.9 \° C = 28.0 kcal[/tex]

where,

c: calorimetry constant
m: mass of water in the calorimeter
ΔT: change in the temperature

According to the law of conservation of energy, the sum of the heat released by the combustion (Qr) and the heat absorbed by the water (Qa) is zero.

[tex]Qr + Qa = 0\\\\Qr = -Qa = -28.0 kcal[/tex]

Carbohydrates contain 4.00 kcal per gram. The mass of sugar that released 28.0 kcal is:

[tex]-28.0 kcal \times \frac{1g}{-4.00 kcal } = 7.00 g[/tex]

A marshmallow containing 7.00 g of sugar is burned in a soda can calorimeter heating .255 kg of water by 12.9 °C.

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