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3. a calorimeter contains 500 g of water at 25°c. you place a hand warmer containing 200 g of liquid sodium acetate inside the calorimeter. when the sodium acetate finishes crystallizing, the temperature of the water inside the calorimeter is 39.4°c. the specific heat of water is 4.18 j/g-°c. how much energy was needed to heat the water?

Energy=specific heat of water x mass of water x water's temperatures

=4.18x500x(39.4-25)

=30096J

as given the equation is

2al + 6 hcl > 2 alcl3 + 3 h2(g)

as per equation two moles of aluminum reacts with six moles of hcl to give two moles of alcl3 and three moles of hydrogen gas

given: three moles of al are present and 7 moles of hcl

for three moles of aluminum nine moles of hcl will be required

however as 7 moles of hcl are present so the limiting reagent is hcl

hcl is going to decide the number of moles of product formed

when six moles of hcl are present = 3 moles of h2 are formed

when one mole of hcl is present == 3/6 mole sof h2 will be formed

when 7 moles of hcl are present = 3 x 7/ 6 moles of h2 will be formed = 3.5 moles of h2