Tammy applies the skills learned from the titration of

Question

Tammy applies the skills learned from the titration of vinegar exercise to the determination of the concentration of phosphoric acid necessary for her biology project. A total volume of 8.22 mL of 0.125 M potassium hydroxide solution was required to completely neutralize 14.32 mL of phosphoric acid (three acidic hydrogens). Calculate the concentration of her phosphoric acid solution.

1. 0.0718 M
2. 0.144 M
3. 0.215 M
4. 0.0239 M
5. 0.645 M

1. One grOup of students forgot to account for the vapor pressure of water when analyzing their data. How would this error affect their mass percent concentration?

1. The mass percent is too high because the pressure they used is too low
2. The mass percent is too low because the pressure they used is too low
3. The mass percent is too high because the pressure they used is too high
4. The mass percent is too low because the pressure they used is too high
5. Vapor pressure does not affect the calculation

 

1. Students who have lab in room 205 had to use ~ 4 mL of 3% H2O2 in order to get a volume of 45 mL of gas, while students in room 212 had to use ~6 mL. Why did the students in 212 need to use more hydrogen peroxide?
   1. The temperature in 212 is much colder than 205.
   2. Hydrogen peroxide decomposes slowly over time. The bottle in 205 must be older.
   3. The pressure in 205 is lower than 212 because of the air conditioning unit.
   4. The stockroom wasn't precise when diluting the 30% H2O2 to 3% solution.
   5. Hydrogen peroxide decomposes slowly over time. The bottle in 205 must be newer.