q1 1. 50.0 g of water are added to a coffee cup calorimeter. Some HCl is then ad

Question

q1 1. 50.0 g of water are added to a coffee cup calorimeter. Some HCl is then added to the calorimeter. This dissolves in the water, forming an HCl solution. A piece of aluminum metal is then added to the calorimeter: it reacts with the IICI already present. During the reaction. the temperature of the water in the calorimeter rose front 22.4 degree C to 28.3 degree C. a) Write a balanced molecular equation for the reaction that occurred. Please indicate the physical states of all the reactants and products. b) Using the calorimeter data given above, the balanced equation for the reaction, and the following standard enthalpies of formation, calculate the number of grams of aluminum that reacted.

Explanation / Answer

2Al(s) + 6HCl(aq) -------> 2AlCl3 + 3H2(g)

delta H0rkn = 3*(delta H0f H2) + 2*(delta H0f AlCl3) - 6*(delta H0f HCl) - 2(*(delta H0f Al) = -405.44 kJ

Now,

heat obtained in the reavtion = mass of water*specific heat of water*rise in temperature of water = 50*4.184*5.9 = 1234.28 J = 1.23428 kJ

Thus, moles of Al reacted = (2*1.23428)/405.44 = 0.0061

mass of Al reacted = moles*molar mass = 0.0061*27 = 0.1644 g

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