Heat and Enthalpy Changes for Chemical Reactions CHM 210 NAME 10 TA LAB TIME AND

Question

Heat and Enthalpy Changes for Chemical Reactions CHM 210 NAME 10 TA LAB TIME AND DAY LAB PARTNER Pre-Lab Questions Answer the following questions after you have read the experiment and have studied calorimetry in you textbook (section 9.2). 1. Calculate the amount of energy (in kJ) required to heat 145 g of water from 20.0°Cto 77.5°C The specific heat of water is 4.184 J/g C 2. Calculate the amount of 5.00 M HCl needed to make 50.0 ml of 1.00 M HCL. 3. A calorimeter contains 75.0 g of 15.00°C water. A 28.0 g gold coin is initially in a beaker of 95.00°C water. The coin is quickly moved into the calorimeter and the water warms to 1621°C For which substance was this process endothermic-water or gold? Explain your reason- ing. a. b. Calculate the specific heat of gold. Show your work

Explanation / Answer

Ans 1

Mass of water m = 145 g

Initial Temperature T1 = 20 C

Final temperature T2 = 77.5 °C

Specific heat capacity of Water Cp = 4.184 J/gC

Energy required = m x Cp x (T2-T1)

= 145 g x 4.184 J/gC x (77.5 - 20) C

= 34884.1 J x 1 kJ/1000 J

= 34.884 kJ

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