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Chemistry Forums for Students => Physical Chemistry Forum => Topic started by: john2520 on October 08, 2012, 03:39:02 PM

Title: Help with calculating the percentage purity of the sample (thermodynamics)
Post by: john2520 on October 08, 2012, 03:39:02 PM

Heres the question: An impure sample of zinc has a mass of 7.35g. The sample reacts with 150.0g of dilute hydrochloric acid solution inside a calorimeter. The calorimeter has a mass of 520.57g and a specific heat capacity of 0.400 J/g C. When the reaction occurs, the temperature of the hydrochloric acid rises from 14.5 to 29.7. What is the percentage purity of the sample? Assume that the specific heat capacity of the hydrochloric acid is 4.184 J/g C. Also assume that all the zinc in the impure sample reacts.

Im not sure how to get the percent can anyone help me with this

Title: Re: Help with calculating the percentage purity of the sample (thermodynamics)
Post by: Borek on October 08, 2012, 04:47:27 PM

How much heat evolved?

Can you use amount of heat produced to calculate number of moles of zinc that reacted?

Note: there is not enough data in the problem as posted, you may need to look for some additional data in tables.