When collecting temperature as a function of time for the reaction of KOH with HCL, which time is most significant

At the completion of reaction.

Explanation:

The time when the reaction take places is the most significant time for measuring temperature of the solution because on this time the temperature will decrease or increase. Some reactions releases heat energy upon completion we called them exothermic reactions whereas some absorb heat energy from the surrounding, decreases the temperature which is known as endothermic reaction so measuring temperature at the completion of reaction is the correct time.

1. 1 mole of anything contains 6.022x10^23 pieces  

d  

2. a  

3. c, number  

5. 1.24x10^24atoms / 6.022x10^23atoms/mole = 2moles h2 atoms  

6. fe2br3 mass = 2moles x mass fe + 3 moles x mass br  

molar mass = grams / number of moles = g/mole  

to find moles = g / molar mass  

to find mass = g = molar mass / moles