The reaction is actually endothermic because delta H is positive, indicating that it absorbing heat.
Answer:
volume is equal to the mass divided by the density (V = M/d).
Precise and Accurate mean the same thing. I would consider measuring more than once to get a precise or accurate measurement.
This would mean the masses of Na and Cl are 22.99g and 35.45g respectively. Therefore, the percent composition of NaCl is 39.3% sodium and 60.7% chloride.
