Can anyone please finish this problem for me? I\'m unsure on the other calculati
ID: 1047648 • Letter: C
Question
Can anyone please finish this problem for me? I'm unsure on the other calculations I need to find. Thank you! CHM 147 Procedure A. Standardization of NaOH Solution Use a small graduated cylinder to measure about 10mL of stock NaOH solution. Combine the 10 mL of NaOH solution with about 400 mL of deionized water in a 500 mL Erlenmeyer flask. Stopper the flask and mix thoroughly over a period of 5 minutes before using. This is all the NaOH solution you will have for the entire experiment; do not waste it! Clean the buret, rinse with distilled water, and then rinse with a few mL of the NaOH solution you have prepared. Before filling buret. Fill the buret with the prepared NaOH solution and open the stopcock to fill the tip. Drain the buret to a volume between 0-5 mL mark. Remember you should not start at 0.00 mL. Check to see that there are no air bubbles in the buret or the tip Weigh 0.5XX grams of potassium hydrogen phthalate (KHC,H.0.) on the analytical balance and place in a 250mL Erlenmeyer flask. Dissolve the solid in 50mL of distilled water, add 2-3 drops of phenolphthalein indicator, and the magnetic stir bar. Place the flask on the magnetic stir plate with a white sheet of paper under the flask to aid in detection of any color change. Record the initial volume in the buret. Add the NaOH from the buret to the acid in the flask. Level of meniseus A sheet of white paper or towel below the fask w help in recognising the calor change st the endpoint Swirl the fark contn uously unsl ane drep af titrant cavies a color change throughout the entire solution Mix the solution using a magnetic stirrer or swirl the flask continuously as you a (Stir the solution at a reasonahle rate hut not too ui the NaOH irl the flask continuously as you add the NaOH.
Explanation / Answer
To calculate concentration (molarity ) of std .NaOH,having known the volume of NaOH used up in the titration, you need concentration of acid that is titrated and the volume of acid titrated.
moles of acid (KHC8H4O4) used=mass/molar mass=0.5g/204.22g/mol=0.00245 moles
volume of acid=50ml=0.050 L
molarity of acid=0.00245 moles/0.05 L=0.049 mol/L
using equation M1*V1=M2*V2
M(NaOH)*V(NaOH)=M(acid)*V(acid) ,M=molarity,V=volume
M(NaOH)=M(acid)*V(acid)/V(NaOH)=0.049 mol/L*50ml/16.87ml=0.145 mol/L=0.145M
concentration of NaOH(std)=0.145M