Question

24. 0.9410 g of phenol (C₆H₅OH) are burned in a bomb calorimeter with a heat capacity of 4.630 kJ/°C . The temperature of the calorimeter increases by 6.590°C. What is the heat of combustion (DH_rxn for the process of burning) of phenol?

a. -30.51 kJ/°C

b. -267.5 kJ/°C

c. -3051 kJ/mol

d. none of these

4. A student buys a Bloomin’ Onion from Outback Steakhouse (1020 Cal, including dipping sauce), and a Hardees’ Monster Thickburger (1420 Cal). Instead of consuming the meal, the student wisely chooses to burn it. If all the energy in the food were used to heat 100.0L of water initially at 25.0°C, how hot would the water end up?

a. 18.4°C

b. 24.4°C

c. 49.4°C

d. none of the above

18. Which pair have the same number of electrons in their Lewis Dot Structures? explain.

a. Na and Ne

b. Na⁺ and Ne

c. Na⁺ and F^-

d. F^- and Ne

Answer 1

24)

Q cal = Ccal*delta T

Q cal = 4.63*(6.59-0.0)

Q cal = 30.51 KJ

This heat is supplied by C6H5OH

Molar mass of C6H5OH = 6*MM(C) + 6*MM(H) + 1*MM(O)

= 6*12.01 + 6*1.008 + 1*16.0

= 94.108 g/mol

mass of C6H5OH = 0.9410 g

we have below equation to be used:

number of mol of C6H5OH,

n = mass of C6H5OH/molar mass of C6H5OH

=(0.941 g)/(94.108 g/mol)

= 9.999*10^-3 mol

delta H = -Qcal/number of mol

delta H = -30.51/9.999*10^-3

delta H = 3051 KJ/mol

Answer: c

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