A student was given only one graduated cylinder to use for this experiment. Afte

Question

A student was given only one graduated cylinder to use for this experiment. After using it to measure 50.0 mL of the assigned acid, the student failed to rinse or dry the cylinder before measuring out the 50.05 mL of the base. Would the calculated Delta H_ be higher, lower, or the same as the literature Delta H_ ? Briefly explain this difference as a result of using only one graduated cylinder for the experiment. Explain how the following changes in the procedure for this experiment would affect the results. A glass beaker was used instead of a pressed polystyrene cup. A pressed polystyrene top was used to cover the polystyrene cup after the acid and base solutions had been mixed.

Explanation / Answer

Q1.

Note that

there is larger amount of base, but the acid is most likely limiting the reaction since it has a 1:1 ratio ( assume monoprotic acid)

Therefore

there will be the SAME heat being released

Note that

When we add 0.5 mL extra

our mass:

M total = 100 g to 100.5 changes, it is higher

but the dT expected will be lower

so the totla Q remains

so

there is NO effect!

Q2.

a)

If the glass beaker is used, then the beaker will not be adiabatic, it will allow heat to flow out

So Q will be lost

So less change in temperature will be recorded

meaning less Q, i.e. less HRxn value

Q2.

this is similar to the question above, if this was done after the reaction, then some heat might escape

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.