A $50\mathrm{.}0-mL$ sample of $0\mathrm{.}90M$ sodium hydroxide is quickly added to a calorimeter containing $50\mathrm{.}0mL$ of $0\mathrm{.}90M$ hydrochloric acid at $20\mathrm{.}1C.$ The equilibrium temperature of the reaction mixture is $26\mathrm{.}7C.$ The reaction mixture weighs $99\mathrm{.}85g.$

$HCl(aq)+$NaOH$(aq)$NaCl$(aq)+H_{2}O$

a$.T=C$

b$.$ If the specific heat of the reaction system is $3\mathrm{.}93\frac{J}{g}*C,$ calculate the heat of reaction using the equation

$H_{rxn}=-S{H}_{\text{s}\text{y}\text{s}\text{t}\text{e}\text{m}}{m}_{\text{s}\text{y}\text{s}\text{t}\text{e}\text{m}}T$

c$.$ Calculate the molar heat of reaction.

When solid potassium bromide $(KBr)$ is dissolved in water, an endothermic reaction occurs.

a$.$ Is heat absorbed or given off by the reaction mixture?

b$.$ Does the water temperature increase or decrease?

c$.$ Is the $H$ of the reaction positive or negative?