a.) A standard displacement reaction is when an active metal displaces hydrogen

Question

a.) A standard displacement reaction is when an active metal displaces hydrogen from an acidic solution. A chunk of calcium metal of mass 18.0 g is placed in a beaker of dilute hydrochloric acid. Given that the acid is the reagent in excess, calculate w of the system in Joules as a result of the reaction. The atmospheric pressure is 0.988 atm and the temperature 23.0 degrees Celsius.

b.) Electrical resistance heating is a common method of generating heat from the passage of electric current. Suppose a current of 2.00 Amps from a 1.50 V source is passed through an electrial resistance heater for 30.00 minutes. The heater is immersed in a water bath. What quantity of heat in calories is transferred to the water?

c.) A sample of liquid rose in temperature by 3.00 degrees Celsius when supplied with 70.00 J of heat. What is the heat capacity in Joules per degree Celsius?

What is the heat capacity in Joules per degree Kelvin?

Explanation / Answer

a) The reaction is Ca+2HCl =CaCl2 +H2

Enthalpy change of the reaction = enthalpies of products - enthalpies of reactants = -877.3 +0 - (3×-167.2)- 0 kj = -542.9 kj.

18 g of Ca = 18/40 mole Ca = 0.45 mole

Heat evolved when 0.45 mole Ca reacts = 0.45 mole × (-542.9) kj = 244.3 kj

Work done = heat change = -244.3 kj

B) heat = volt × current × time = 1.5 volt× 2.00 amp× 30×60 seconds = 5400 joules = 5400/4.2 calories = 1285.7 xalories

C) heat capacity =70/3 j/ degree C = 23.33 Joules/C = 23.33Joules/ K

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.