Need help with 8. The correct answer is circled. Thanks! 7. A 275 g sample of ni
ID: 1036688 • Letter: N
Question
Need help with 8. The correct answer is circled.Thanks! 7. A 275 g sample of nickel at 100.0PC is placed in 100.0 mL of water at 22.0PC. What assumi noheatislosttothe surroundings? The specific heat capacity of Ni is 044410g0 The density of water is 100 erature of the mixcture L and the specific heat capacity of water is 4.18 mg? a) 39.6°C ) 40.8? c) 61.0C d) 79.2°C e) 82.4°C Ni + wider 122.1 (Te-loo)I8T1 16 -122 . ITE +12210 s 418TE-91? 8. When 5.70 g of KBr (molar mass- 119.0 g/mol) is added to 50.0 g of water at 25.0°C in a constant pressure calorimeter, the Assuming that the specific heat of the solution i 418 J g C calculate ?? (in temperature of the water decreases to 21 1°C kJ/mol KBr) for the reaction: S.10 c) ?? " +9,5 kJ 9. Which substances below have a standard enthalpy of formation equal to zero? I. H,00) LW. N(g) 12(s) a) II, IV, and V d) Il and IV e) 11,?, and rv 10. Consider the following reaction: Use the following data to calculate AH for reaction. AH (NO) 34 kJ/mol AHo (H,0)- -286 k/mol ???? INOJ "-207 kJ/mol (NO)-90 kJ/mol
Explanation / Answer
Ans 8 :e) +19 KJ
q = m . c . delta T
m = mass of solution = 5.70 + 50.0 = 55.7 g
So putting all the values we get :
q = 55.7 x 4.18 x (25-21.1)
= 908.0214 J
or 0.908 KJ
So for 5.70 g of KBr , the heat is 0.908 KJ
then for one mole (119.0 g) , it will be :
= (119.0 x 0.908) / 5.70
= 19 KJ