Question
please just use dimensional analysis
B. Determination of the molarity of an unknown acid Your grade wil be determined by how dosely your experimental value agrees with the true value for your unknown 1. 2. Take a acid is (and therefore reacts in a 11 ratio with the titrant) write small clear and dry beaker to door to obtain an unknown ack inom down the unknown number 3. y Be sure to and 10.00 of the r instructor, 4. then titrate the unknown into an Erlenmeyer flask, add 2 drops of indicator (and water if you like) 5. Extra unknown and sample to the endpoin trials, Record your data 6. Rinse solution can be poured down the drain. Rinse the storage bottle Run and away as 7. volume computer program (be sure to enter the volume of base used from your data tables when prompted fr Answer of base). on the printout using dimensional analysis, and staple it to your lab report the question Table 3: Titration of Unknown Acid Unknown Trial 1 Trial 2 Trial 3 Volume of unknown ID. 00 mL. 10 00 mL 0.00 Initial burette reading o oo mL oso 3 ml Final burette reading 21.56 mL 2g. s mL 15 Volume of base used 215 mL. 1. Calculate the molarity of the unknown acid for each trial using dimensional analysis (hint: start with mL of base used). You must show all unit conversions no short cuts! Avg Trial 3 Trial 2: Trial 1 2. Suppose you analyzed 25.00 mL of your unknown using a 0.3215 M KoH solution, how many mL would be required to reach the endpoint? Use dimensional analysis.
Explanation / Answer
1. moles of NaOH used = moles of acid present in solution
since Molarity of NaOH is not given. We would assume the molarity as 0.12 M NaOH (remember to feed the correct value from your experiment here).
Trial 1
moles acid = 0.12 x 27.56 = 3.3072
molarity of unknown acid = 3.3072/10 = 0.33072 M
Similarly for other trial runs can be calculated
2. volume of NaOH needed = 0.33072 x 25/0.3215 = 25.72 ml
once again you must confirm the exact molarity of NaOH given in your experiment to get the correct values.
