The combustion of 1.00 mol of glucose, C6H12O6, releases 2820 kJ of heat. If 2.0 g of glucose is burned in a calorimeter containing 1.0 kg of water, and the temperature increases by 3.5 oC, what is the heat capacity of the calorimeter?

Respuesta :

Answer:

The heat capacity of the calorimeter is 4.76 kJ/°C

Explanation:

Step 1: Data given

1.00 mol of glucose releases 2820 kJ of heat

Mass of glucose = 2.0 grams

Mass of water = 1000 grams

The temperature increases with 3.5 °C

Step 2: Calculate moles

moles glucose = mass glucose / molar mass glucose

moles glucose = 2.0 grams / 180.16 g/mol

moles glucose = 0.0111 moles

Step 3: Calculate heat produced by the combustion

Heat produced = 2820 kJ/mol * 0.0111 moles

Heat produced = 31.302 kJ = 31302 J

Step 4: Calculate heat absorbed by the water

Q = m*c*ΔT

⇒ with m = the mass of water = 1000 grams

⇒ with c = the specific heat of water = 4.184 J/g°C

⇒ with ΔT = The change in temperature = 3.5 °C

Q = 1000 * 4.184 *3.5

Q = 14644 J absorbed by the water

Step 5: Calculate heat basorbed by the calorimeter

Q = 31302 - 14644 = 16658 J absorbed by the calorimeter

Step 6: Calculate the heat capacity of the calorimeter

c= 16658 J / 3.5 °C

c = 4759 J/°C = 4.76 kJ/°C

The heat capacity of the calorimeter is 4.76 kJ/°C

The specific heat capacity of the calorimeter is 4.759 kJ/⁰C.

The molar mass of glucose is calculated as;

C₆H₁₂O₆ = (12 x 6) + (1 x 12) + (16 x 6) = 180 g/mol

The number of moles in 2g of glucose;

[tex]mole = \frac{2}{180} \\\\mole = 0.0111 \ mol[/tex]

The heat added by 0.011 mol of glucose

1 mole -------------- 2820 kJ

0.0111 mole --------- ?

[tex]= 0.0111 \times 2820 \ kJ\\\\= 31.302 \ kJ\\\\= 31,302 \ J[/tex]

The heat of the given water;

[tex]Q = mc\Delta \theta \\\\Q = (1000)(4.184)(3.5)\\\\Q = 14,644 \ J[/tex]

The heat absorbed by the calorimeter is calculated as follows;

[tex]\Delta Q = 31,302\ J - 14.644 \ J\\\\\Delta Q = 16,658 \ J[/tex]

The specific heat capacity of the calorimeter is calculated as follows;

[tex]C_c = \frac{\Delta Q }{\Delta \theta} \\\\C_c = \frac{16,658}{3.5} \\\\C_c = 4.759 \ kJ/^0C[/tex]

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