9) A 83.0 g metal absorbs 181.2 J of heat and the temperature increases from 20.
ID: 489186 • Letter: 9
Question
9) A 83.0 g metal absorbs 181.2 J of heat and the temperature increases from 20.0 C to 25.4 C. What is the specific heat of this metal in J/(g*C)? Note: To avoid any sig fig issues, keep 2 decimal places for your input!!
10) Which one is correct about the following process? CH4 + 2 O2 --> CO2 + 2 H2O a) It is endothermic with negative enthalpy change. b) It is exothermic with positive enthalpy change. c) It is exothermic with negative enthalpy change. d) It is endothermic with positive enthalpy change.
11) 65.8 mL of 1.00 mol/L NaOH reacted with 100.0 mL of 1.00 mol/L HCl solution and the temperature increased from 20 to 22 C. How many moles of HCl and NaOH are neutralized? Note: to avoid any sig fig issues, please use regular decimal instead of scientific notation and keep 3 sig figs for your input!!
12) Equal mass of water and iron are mixed in a perfect calorimeter and allow heat to exchange until thermal equilibrium is achieved. If the initial temperatures of water and iron are 20 C and 80 C respectively, which one is correct about the final temperature? a) It will be between 20 C and 50 C and is just slightly lower than 50 C b) It will be between 50 C and 80 C c) It will be between 20 C and 50 C but probably is much closer to 20 C than 50 C d) It will be exactly 50 C
Explanation / Answer
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10) Which one is correct about the following process?
CH4 + 2 O2 --> CO2 + 2 H2O
a) It is endothermic with negative enthalpy change.
b) It is exothermic with positive enthalpy change.
c) It is exothermic with negative enthalpy change. -----------ANSWER
d) It is endothermic with positive enthalpy change.
CH4(g) + 2O2(g) CO2(g) + 2H2O(g) H = -802 kJ/mol
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9) A 83.0 g metal absorbs 181.2 J of heat and the temperature increases from 20.0 C to 25.4 C. What is the specific heat of this metal in J/(g*C)? Note: To avoid any sig fig issues, keep 2 decimal places for your input!!
Q=m s delta t
Specific Heat formula is: c = Q / (m × T)
Where:
c: Specific Heat , in J/(kg.K)
Q: Heat required for the temperature change, in J
T: Temperature change, in K
m: Mass of the object, in kg
PLUGGING VALUES IN ABOVE EQUATION
S = 181.2 / (0.083 * 5.4)
=404.28380187416 J/kg.C------------------------ANSWER
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