Dylan measured out 100.0 mL of 1.0 M HCL and poured it into his styrofoam cup ca

Question

Dylan measured out 100.0 mL of 1.0 M HCL and poured it into his styrofoam cup calorimeter. Next he weighed out 0.10g of magnesium, Mg( At. Wt. = 24.3).He found the initial temperature to be 24.2*C and his final temperature to be 26.3*C mus tbe made about the 1.0 M HCL solution? What is the enthalpy change per mole of Mg, if the net ionic reaction is Mg(s) + 2H+(aq) --> Mg2+(aq) + H2(g)?

A Biology experiment requires the preparation of a water bath at 37*C (body temperature). The temperature of the cold water tap is at 22.0*C, and the temperature of the hot tap water is 57.0*C. If Casey starts 90.0g of cold water, what is the mass of the hot water must be added to reach 37.0*C? (Specific heat of water is 4.18 J/g-K1.

Explanation / Answer

mmol of HCl = MV = 1*100 = 100

mmol of Mg = mass/MW = 0.10/24.3 *1000 = 4.1152

Ti = 24.2°C, Tf = 26.3°C

dT = 26.3-24.2 = 2.1°C

HRxn = -Qsolution / mol

Qsolution = m*C*(Tf-Ti)

Qsoln = 100*4.184*(2.10) = 878.64 J

HRxn = -878.64 J / 4.1152 mmol

J/mmol = kJ/mol

HRxn = -213.51 kJ/mol

Q2

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