# Chemistry

posted by Jessica

3.25g of zinc was added to 50cm^3 of a 4.0 molar dm^-3 HCl. When the reaction was completed the temperature rose by 28 degrees celcius.
(a) Is the reaction exothermic or endothermic?
(b)All the zinc dissolve in this reaction. How many moles of zinc reacted?
(c) How many moles of acid are there in 50cm^3 of a 4.0 molar dm^-3 HCl.

(d) Write a balance equation for the reaction b/w zinc and HCL.

(e) Which of the two is used in excess? Why?

(g) Calculate the heat change when 3.25g of zinc reacts with 50 cm^3 of a 4.0 molar dm^-3 HCl.

(h) calculate the enthalpy change for the reaction between zinz and HCl.

1. DrBob222

The reaction is exothermic because heat is evolved.
mols Zn = grams/atomic mass = ?
mols acid = M x L = ?
Zn + HCl ==> ZnCl2 + H2 You balance.
The reagent in excess is not the limiting reagent.
q = mass H2O x specific heat H2O x delta T.
h) dH = q
Note that this is in J/rxn and not J/mol or kJ/mol
Also, not the correct spelling of celsius.

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