The image represents a sound wave as it goes through several changes. Describe how the wave changes. Where does it get louder? Where does it get softer? How does the pitch change? How do you know?

To find the molar enthalpy change follow these steps:

1) find the amount of heat released in this experiment, that is Q=mcT, where m is the mass or volume of solution used, T is the rise/drop in temperature and C is the specific heat capacity of water which is 4.18

Q= 500 × 4.18 ×(70-11)= 123310 J

2) divide this value by 1000 to convert it into kJ

123310÷1000=123.31

3) divide the value of energy released by number of moles , that is, mass/Mr

number of moles of Nitrogen = 20 ÷(14+14)                                                    = 5/7 moles molar enthalpy change= 123.31÷5/7                                         = 172.634 mol/kJ