Question

15.48 g of nickel sulfate (MM 154.75 g/mol) was dissolved in 100.00 mL of water. The initial temperature was 20.00 oC, and the final temperature was 25.06 oC, The specific heat capacity of the reaction mixture was 4.18J g- oC-. What is the heat transferred, Q? A. 2442 J B. 2115 J C. 327 J D. 418 J I got 327 J, but it gets marked as wrong. Why?

15.48 g of nickel sulfate (MM 154.75 g/mol) was dissolved in 100.00 mL of water. The initial temperature was 20.00 oC, and the final temperature was 25.06 oC, The specific heat capacity of the reaction mixture was 4.18J g- oC-. What is the number of moles of nickel sulfate dissolved. A. 100 mol B. 10.0 mol C. 1.00 mol D. 0.100 mol My calculations vary between .100 mol and 1.00 mol, can someone double check my answers?

Answer 1

Part a

Mass of water = volume x density

= 100 mL x 1 g/mL = 100 g

Total mass of mixture = mass of nickel sulfate + mass of water

= 15.48 + 100 = 115.48 g

Specific heat capacity of mixture Cp = 4.18 J/gC

Initial temperature T1 = 20 C

Final temperature T2 = 25.06 C

Heat transferred

Q = m x Cp x (T2-T1)

= 115.48 g x 4.18 J/gC x (25.06 - 20) C

= 2442 J

Option A is the correct answer

Part b

moles of nickel sulfate dissolved = mass/molecular weight

= 15.48 g / 154.75 g/mol

= 0.1 mol