Chemistry

Given that the solubility of sodium chloride is 36 grams per 100 grams of water. Which of the following solutions would be considered supersaturated?

A. dissolve 5.8 moles of NaCl in 1 L of water

B. dissolve 1.85 moles of NaCl in 300 ml of water

C. dissolve 3.25 moles of NaCl in 500 ml of water

D. none of the above

My husband and I are arguing...I think that the answer is A and he thinks it's C--please help and explain. Thanks.

  1. 👍 0
  2. 👎 0
  3. 👁 1,426
  1. It's a tie between you and your husband. I don't think either is correct.
    I looked up the molar mass of NaCl and found it to be 58.442.
    So A is 5.8 x 58.442 = about 338 g
    B is 1.85 x 58.442 = 108.11 g
    C is 3.25 x 58.442 = 189.99 g
    D--

    How much can dissolve.
    A is 36 x 1000/100 = 360 g so 338 should dissolve easily.
    B is 36 x 300/100 = 108 which is close and I might call it saturated but not supersaturated.
    C is 36 x 500/100 = 180 g and it can dissolve nearly 190 g which eliminates C. I pick D. Check my thinking.
    One note: Note that the problem states "per 100 GRAMS water" while the answers are in L and mL. I have assumed the density of water is 1.00 g/mL which makes 1 mL have a mass of 1.00 gram. I don't know if this was an attempt to throw you off or not. Also, some profs may argue that we shouldn't use that many places in the molar mass of NaCl. However, if we use 58.4 (three significant figures to agree with 3 s.f. for the moles) then 1.85 x 58.4 = 108 which still makes a saturated solution. While we are playing these IF games, we might argue that the 300, 500, and 1 L contain only 1 s.f., THEN, some of the conclusions might change. However, I think the intent of the problem is for the answer to be none of these.

    1. 👍 0
    2. 👎 0
  2. Dr Bob,

    First let me thank you for your help and explanations, so that I can understand what I'm supposed to be doing--it's much appreciated!

    I have a question though, at what point do I know that a solution would be saturated, supersaturated, unsaturated, etc. I know the word definitions for these, but how do you know that if your answer for option "b" above was 108.11, then how do you know that it is not saturated, or supersaturated? I know that supersaturated would mean that the substance would not completely dissolve, but how do you tell in regards to numbers? I'm so confused! :-(

    1. 👍 0
    2. 👎 0
  3. First, let me apologize because I goofed and not just a little but a lot. The correct answer is not D.
    Unsaturated means that the solute has dissolved and more can dissolve.
    Saturated means that the solute has dissolved and that one more crystal will not dissolve.
    Supersaturated means (and this may sound confusing) that more of the solute has dissolved than normally possible. How can that happen? We can dissolve the solute in a hot solvent, then very carefully cool the solvent to room temperature. SOME solutions will hold all of the solute without any of it precipitating. The usual process is for it to precipitate (crystallize) but SOME solutes will stay in solution when, technically, they shouldn't. (In the case of a supersaturated solution, one can scratch the sides of the test tube with a stirring rod, or shake the solution, or drop in a crystal to act as a seed and the excess solute crystallizes almost instant. I made the error because I was trying to go back and forth between the question and my typing and I reversed some of the numbers.
    Here are the answers (with my comments in bold) again
    So A is 5.8 x 58.442 = about 338 g
    B is 1.85 x 58.442 = 108.11 g
    C is 3.25 x 58.442 = 189.99 g
    D--

    How much can dissolve.
    A is 36 x 1000/100 = 360 g so 338 should dissolve easily.This is OK.

    B is 36 x 300/100 = 108 which is close and I might call it saturated but not supersaturated. So we have dissolved 108.11 and it can hold 108 so this could be supersaturated depending upon how you want to handle the significant figure thing. I think the spirit of the question calls for you to decide this is a saturated solution.

    C is 36 x 500/100 = 180 g and it can dissolve nearly 190 g which eliminates C. I pick D. This is the correct answer. The solvent CAN hold 180, but the 3.25 M tells us it HAS almost 190 g dissolved in it (note where I reversed the numbers in my mind) so it is clearly supersaturated. It has more solute (190 g) than the solvent can hold normally (180 g).
    I hope this answer is sufficient and I certainly hope I didn't confuse you with my original answer. You were wise to ask me to explain it again--I noted the error when I started typing. Thanks for the heads up.

    1. 👍 0
    2. 👎 0

Respond to this Question

First Name

Your Response

Similar Questions

  1. chemistry

    when chlorine gas is bubbled into a solution of sodium bromide, the sodium bromide reacts to give bromine a red brown liquid and sodium chlorine. A solution was made by dissolving 20.0g of sodium bromide in 100.0 g of water. After

  2. math

    Three students have made multiple measurements of the solubility of sodium chloride (in g of NaCl per 100 g of water). Their results are summarized in the table below. The correct value for the solubility of sodium chloride is

  3. Chemistry

    A 10.00 gram solid sample consisting of a mixture of sodium chloride and potassium sulfate is dissolved in 100.0 mL of water is combined with another 200.0 mL solution that contains excess aqueous lead(II) nitrate. Upon mixing the

  4. Chemistry

    A sample of Manganese (II) Chloride has a mass of 19.8 grams before heating, and 12.6 grams after heating until all the water is driven out. Based on this information, how many water molecules were attached to each molecule of

  1. Chemistry

    If a solution has a total mass of 26.7g and is 8.36 % by weight in sodium chloride, what mass of sodium chloride is present in the solution? How many moles of dextrose (C6H12O6) are in 414mL of solution with a concentration of

  2. CHEM MOLES !@@!

    Mole Calculation Worksheet 1) How many moles are in 15 grams of lithium? 2) How many grams are in 2.4 moles of sulfur? 3) How many moles are in 22 grams of argon? 4) How many grams are in 88.1 moles of magnesium? 5) How many moles

  3. Chemistry

    The solubility of sugar is 204 g/ 100 g water at 20 °C. How many grams of water are needed to dissolve 612 grams of sugar at the same temperature?

  4. Organic Chemistry

    1) Calculate the partition coefficient of caffeine in water/methylene chloride from the following data: 10.3 g/100 mL for methylene chloride and 2.04 g/100 mL for water. 2. A student is sure that 0.500 grams of caffeine is

  1. chemistry

    A certain substance has a solubility of 12 grams in 100 grams of water at 20°C. This means that _____ the substance will begin to dissolve when 12 grams are present in solution when 12 grams of the substance are stirred into a

  2. chemistry

    The directions state "weigh about 5 grams of sodium chloride". Give minimum and maximum amounts of sodium chloride that would satisfy these instructions.

  3. chemisty

    If 15 grams of copper (11) chloride react with 20 grams of sodium nitrate, how much sodium chloride can be formed? Hint: you will need two stochiometry problems to determine which reactants limit the amount of NaCl produced? How

  4. Chemistry

    1. Hydrogen gas combines with oxygen gas to yield water. if 15 g O2 is present in the reaction, compute how much water will be produced. 2. Ten (10)grams methane gas combines with oxygen gas to form water and carbon dioxide. How

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