Chemistry

We performed a lab in class about a month ago concerning different types of equilibrium. One particular portion of the lab adding 5 mL of .3M HCl to 5 mL of .3 M Pb(NO3)2. After a precipitate finally formed, 8 mL of water was added to dissolve PbCl2.

One of my lab questions asks, "Explain why PbCl2 did not precipitate immediately on addition of HCl. (What condition must be met by [Pb+2] and [Cl-] if PbCl2 is to form?

I'm stumped on this question. By multiplying the concentrations of Pb+2 and Cl- like so:
(.3)x(.3)^2
I get a value of .027, which is higher than most Ksp values I've seen for lead chloride. Why, then, would the precipiation of the solid not be immediate upon the addition of HCl?

I don't know. What I wonder about is the effect of the acid pH on the ksp. This was not neutral water.

PbCl2 forms at least a couple of complex ions with HCl. One is PbCl3^- and the other more common one is PbCl4^-2. Usually, however, the PbCl2 will form first before some of it dissolves by forming the complexes.

Your question doesn't provide much about the manner in which the HCl was added to the Pb(NO2)2. There is the possibility, however, that the HCl was added in small increments and the PbCl2 didn't ppt right away because Ksp was not exceeded right away. The question about "what must be so about Pb and Cl" almost begs the answer "[Pb^+2][Cl^-]^2 must be greater than Ksp before pptn will take place.

  1. 👍
  2. 👎
  3. 👁
  1. the pbcl2 had not the right concentration level

    1. 👍
    2. 👎
  2. I think that your concentrations of Pb and Cl are lower than you think they are. If you were to add 1L of 1M Pb+ to 1L of 1M Cl-, remember that you now have doubled the amount of liquid. You now have 2 L of liquid with 1 mole of Pb+ and 1 mole of Cl- in it. As you add your Cl-,the value gets squared, so, you will eventually get to a point where it puts you over your needed Ksp.

    1. 👍
    2. 👎
  3. 123

    1. 👍
    2. 👎

Respond to this Question

First Name

Your Response

Similar Questions

  1. Pre-Algebra

    Two months ago, the mean daily rainfall in a local city was 9.4 cm. The mean absolute deviation was 3.5 cm. Last month, the mean daily rainfall in that city was 11.5 cm, and the mean absolute deviation was 1.6 cm. Which statement

  2. statistics

    The data represents the daily rainfall (in inches) for one month. Construct a frequency distribution beginning with a lower class limit of 0.00 and use a class width of 0.20. The frequency of the first class limit (0.00 – 0.19)

  3. Apex personal finance

    Mack opened a CD 10 years ago at an interest rate of 7.8% compounded monthly. According to the rule of 72, when did she have half as much money as she does now? A. About 9.2 years ago B. About 4.6 years ago C. About 3.9 years ago

  4. microeconomics

    1. Suppose that an increase in the price of carrots from $1.20 to $1.40 per pound raises the amount of carrots that carrot farmers produce from 1.2 million pounds to 1.6 million pounds. Using the midpoint method, what would be the

  1. math

    Solve the problem. A shirt company has 4 designs that can be made with short or long sleeves. There are 5 color patterns available. How many different types of shirts are available from this company? a. 9 types b. 40 types c. 11

  2. Math 140

    To help pay for a class trip at the end of the senior year, the junior class at a high school invests $1800 from a fund-raiser in a 18-month CD paying 2.6% interest compound monthly. Determine the amount the class will receive

  3. chemistry

    When acetone is added to saturated sodium chloride, the equilibrium shifts toward the right. What is the role of acetone in shifting the equilibrium toward the right? any help would be appreciated. My TA is of no use in explaining

  4. math

    An airline with two types of airplanes, P1 and P2, has contracted with a tour group to provide transportation for a minimum of 400 first class, 900 tourist class, and 1500 economy class passengers. For a certain trip, airplane P1

  1. Science please help

    List and briefly outline the six different periods into which the Paleozoic era is divided. The six periods: 1:Cambrian, which was 545 million years ago. 2:Ordovician, which was 490 million years ago. 3:Silurian, which was 445

  2. Algebra

    A student receives his grade report from a local community college, but the GPA is smudged. He took the following classes: a 2 hour credit art, a 3 hour credit history, a 4 hour credit science course, a 3 hour credit mathematics

  3. chem 221 #3

    during the preparation of synthetic banana oil lab. Calculate the amount of isopentyl acetate that should be present in the reaction mixture at equilibrium based on 300 mmol of acetic acid and 150 mmol of isopentyl alcohol as

  4. Algebra

    My science class is pretty small. There are just 18 students in the class. My teacher, Mr. Burnett, has an unusual system for picking lab partners. He has given each student a number from 1 to 18, and on lab days, he pulls two

You can view more similar questions or ask a new question.