Please show your steps! Some sodium hydroxide pellets were placed in an Erlenmey
ID: 1029489 • Letter: P
Question
Please show your steps!
Some sodium hydroxide pellets were placed in an Erlenmeyer flask and dissolved in approximately 50mL of water. This solution was then transferred to a buret. 3.00mL of 1.0 molar nitric acid was diluted into approximately 50mL of water in another flask. It required 22.67mL of the sodium hydroxide solution to titrate the dilute nitric acid solution to an endpoint. What can you say about the mass of sodium hydroxide pellets initially added to the Erlenmeyer flask?
A) More than a gram was used.
B) Exactly a gram was used.
C) Less than a gram was used.
D) Cannot be determined, because the final volume of the sodium hydroxide solution is unknown.
E) Cannot be determined, because the final volume of the diluted nitric acid solution is unknown.
Explanation / Answer
Solution:- 3.00 mL x (1L/1000mL) x (1.0 mol HNO3/1L) = 0.003 mol HNO3
HNO3(aq) + NaOH(aq) -----> H2O(l) + NaNO3(aq)
From this equation, they react in 1:1 mol ratio. So, at end point, 22.67 mL of NaOH must contian 0.003 moles of NaOH.
Now, we can calculate it's moles present in 50 mL solution and on multiplying by molar mass grams could be calculated as..
50 mL x (0.003 mol/22.67 mL) x (40.0 g/1mol) = 0.265 g NaOH
So, the right option is C) Less than a gram was used.