51.5g of aqueous phosphoric acid is mixed with 52.0g of aqueous sodium hydroxide in a calorimeter. The initial temperature was 22.3 Celsius (C) and the final temperature was 31.5 Celsius (C). The calorimeter constant is 31.72 J/C and the heat capacity of the final system is 4.00 J/gC. Based on this data the enthalpy of the reaction (Hrxn) would be calculated as kJ(report to 3 sig figs and include appropriate sign).

4,10kJ

Explanation:

The reaction of phosphoric acid (H₃PO₄; MW: 97.994 g/mol ) with sodium hydroxide (NaOH; MW: 40 g/mol) is:

H₃PO₄ + NaOH ⇄ H₂PO₄⁻ + Na⁺ + OH⁻

Now, the energy produced for the change in temperature in a calorimeter is:

Q = -H×m×ΔT - C×ΔT

Where H×m×ΔT is the energy absorbed for the system and C×ΔT is the energy absorbed for the calorimeter.

Replacing:

Q = -4.00J/g°C × 103,5g × (31,5°C-22,3°C) - 31,72J/°C × (31,5°C-22,3°C)

H is heat capacity of the system, ΔT is change in temperature, m is total mass of the system: 52,0g + 51,5g = 103,5g and C is calorimeter constant.

Q = -4100J ≡ -4,10kJ

I hope it helps!

passing a magnet thought the

mixture , because iron gets attracted to magnet .

answer: c. the experiment shows that the red substance experienced a chemical change.

explanation: chemical change is the change in which chemical composition of the substance changes. physical change is the change in which there is no change in chemical composition.

chemical changes are accompanied by following changes:

a) precipitate formation

b) energy is released or absorbed

c) formation of bubbles

d) change in color

as it is given that the red color has disappeared and there is production of gas, it means the red substance has undergone a chemical change.

e