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##### High School Chemistry Forum / Re: Calorimetry Question

« Last post by**billyboy**on

*April 09, 2021, 11:37:00 AM*»

c= 4.2 j/g*C

deltaT = 31.8*C - 23.5*C

= 8.3*C

mass of HNO3 = 55.0mL/1 x 1g/1mL

= 55.0g

Q= mcDeltaT

= (55.0g)(4.2j/g*C)(8.3*C)

= 1917 x 1kj/1000j

= 1.917kj

n= m/M

= 55.0g/63.02g/mol

= 0.873mol

DeltaH= -Q/n

= -(1.917kj)/0.873mol

= -2.20kj/mol

But the answer should be -54kj/mol

deltaT = 31.8*C - 23.5*C

= 8.3*C

mass of HNO3 = 55.0mL/1 x 1g/1mL

= 55.0g

Q= mcDeltaT

= (55.0g)(4.2j/g*C)(8.3*C)

= 1917 x 1kj/1000j

= 1.917kj

n= m/M

= 55.0g/63.02g/mol

= 0.873mol

DeltaH= -Q/n

= -(1.917kj)/0.873mol

= -2.20kj/mol

But the answer should be -54kj/mol