Lab: Enthalpy Answers

What were the learning goals of this lab experiment? Check all that apply.

and the volumemass✔ temperature change during the reaction.

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reactions ✔ gave off absorbedneither gave off nor absorbed heat.

’s law allows you to find the net enthalpy of the magnesium combustion by adding the enthalpies of intermediate reactions.

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To find the enthalpy of a reaction in the lab, you measured the volume✔ masstemperature of the reactants

Reaction(s) 123✔ 1, 2, and 3 released heat.

The enthalpy of the magnesium combustion is -817✔ -654-245 kJ/mol.

Suppose that during the experiment, a student forgot to put the lid on the calorimeter. What is the most likely error and reason?

The actual enthalpy of the magnesium flare reaction is –603 kJ/mol. Your experimental value was likely different. Check all that apply.

Assuming an experimental value of enthalpy of –655 kJ/mol and a true value of –603, what is the percent error of the experiment? Use a calculator and round to the nearest hundredth as well as the absolute value of the percentage.%

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Instant hot and cold packs are found in many common stores and work when two substances react. Depending on the substances that react, the reaction either absorbs heat or gives off heat.The enthalpy of a hot pack is ✔ negativepositivezero

Reaction ✔ 12X 3 released the most heat per mole of reactant.

Magnesium combustion gives off a little✔ gives off a lot ofabsorbs a littleabsorbs a lot of heat.

because the reaction absorbs heat✔ gives off heatdoes not change temperature.

In both Reactions 1 and 2, the temperature change was ✔ positivenegativeneutral, meaning that the