In an experiment to determine δh for the reaction between hbr and naoh , 43.6 ml of 1.08 m hbr at 19.95 °c is placed in a coffee cup calorimeter which has a heat capacity of 7.99 j/°c. 43.6 ml of 1.08 m naoh at 19.95 °c is added to the acid solution in the calorimeter and quickly mixed. a final temperature of 26.88 °c was recorded. what is δh for this reaction, in kj? assume that the specific heats of all solutions are the same as for pure water (4.18 j g-1 °c-1), and that all solution densities are 1.00 g/ml. don't forget to put the proper sign on your δh value.

ΔH = -57.78kj/mol

Explanation:

Assumptions

These are solutions, not pure water. The specific heat of water is 4.184 J/goC. Assume that these solutions are close enough to being like water that their specific heats are also 4.1984 J/goC.

  the heat  evolved will be

q = mcΔt

first of all convert ml to grams

(43.6 mL + 43.6 mL ) = 87.2mL of solution.

density of water=1g/ml

87.2 mL X 1     g/ml        =  87.2 grams of solution.

(mass = Volume X Density)

Find the temperature change.

      Δt =tfinal - tinitial = 26.88oC - 19.95oC = 6.93oC

   q = mcΔt

      = 87.2 grams X 4.184 J/goC    X 6.9oC

      = 2.52 X 10^3 J

This is the heat gained by the water, but in fact it is the heat lost by the reacting HBr and NaOH, therefore q = -2.52 x 10^3 J.

 i.e. it is an exothermic reaction, heat was lost to the water and it got warmer

to find the how much of HBr that was used in mol

43.6 mL of HBr X 1.00 mol HBr/ 1000 mL HBr = 0.0436 mol HBr

same quantity of base NaoH was used

. molar enthalpy = J/mol = -2.52 x 10^3 J /  0.0436 mol

-57.78kj/mol

Therefore, for the neutralization of HBrl and NaOH, the enthalpy change, often called the enthalpy of reaction is ΔH = -57.78kj/mol

because it says use -2,0,and 2 for x, we can plug those numbers into the equation. y/4=3/4(-2)+2   y/4= -1 1/2 +2 now to get x by itself, we can multiply each side by 4. y=-6+8 which equals y=2 when x=-2. now you can do the same thing with 0 and 2 as x. you get y=8 when x=0 and y=14 when x=2.

x   |   y

-2 |   2

0   |   8

2   |   14

the answer is ampere

the ampere is used to measure electricity. an ampere is a unit of electric current equal. a unit of measure for the flow of current in a circuit. one ampere is the amount of current flow provided when one volt of electrical pressure is applied against one ohm of resistance.