PLEASE HELP 1-A researcher studying the nutritional value of a new candy places

Question

PLEASE HELP

1-A researcher studying the nutritional value of a new candy places a 3.00-gram sample of the candy inside a bomb calorimeter and combusts it in excess oxygen. The observed temperature increase is 2.55 °C. If the heat capacity of the calorimeter is 37.10 kJ·K–1, how many nutritional Calories are there per gram of the candy?

2-In a constant-pressure calorimeter, 50.0 mL of 0.340 M Ba(OH)2 was added to 50.0 mL of 0.680 M HCl. The reaction caused the temperature of the solution to rise from 23.68 °C to 28.31 °C. If the solution has the same density and specific heat as water (1.00 g/mL and 4.184 J/g·K, respectively), what is H for this reaction (per mole of H2O produced)? Assume that the total volume is the sum of the individual volumes.

3-If the heat of combustion for a specific compound is -1470.0 kJ/mol and its molar mass is 52.79 g/mol, how many grams of this compound must you burn to release 678.20 kJ of heat?

Explanation / Answer

1.
q = Cp*DT

heat released = 37.1*2.55 = 94.605 kj

heat released = 94.605 kj = 22.611 kcal

nutritional Calories = 22.611*10^3/3 = 7537 cal/gram

2. Ba(OH)2 + 2HCl ---- > BaCl2(aq) + 2H2O(l)

No of mol of Ba(OH)2 = 50/1000*0.34 = 0.017 MOL

No of mol of HCl = 50/1000*0.68 = 0.034 mol

heatreleased = msDT

              = 100*4.184*(28.31-23.68)
  
        = 1937.2 joule = 1.937 kj

DHrxn = 1.937*1/0.017 = 113.94 kj

   per mol of water = 113.94/2 = -56.97 kj/mol

3)

No of mol of compound required = 678.2/1470 = 0.461 mol

mass of compound required = 0.461*52.79 = 24.33 grams

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