50mL of 1 mole of HCI was added to 50mL of 1 mole NaOH. What temperature change would be noticed?

You perform a neutralization reaction with the formation of water, and $N a C l \left(a q\right)$...
$N a O H \left(a q\right) + H C l \left(a q\right) \rightarrow N a C l \left(a q\right) + {H}_{2} O \left(l\right)$...
Given some extra data, we could calculate the heat associated with the formation of $0.05 \cdot m o l$ of $N a C l \left(a q\right)$...of course you have not really specified the concentration of the acid or hydroxide solutions...