Considering the following precipitation reaction: Pb (NO3)2 (aq) + 2KI (aq) ----> PbI2 (s) +2KNO3 (aq)?
Answer is A. Note that the other three are listed as (aq) = aqueous? That means they are ions in solution. But PbI2 is listed as (s) = solid = precipitate In truth, even the PbI2 has SOME ions in solution, but the solubility product is 7.47x10^-9, so there isn't very much.
How do you determine precipitation between two compounds?
KOH (aq) + MgBr2 (aq) --> ??? Knowing that this is a double replacement reaction, we can predict the products by "flip flopping" the positive and negative "ions". KOH (aq) + MgBr2 (aq) ---> KBr + Mg(OH)2 Then check each of the predicted products in the solubility rules* to see if either is insoluble. KBr is soluble in water, but Mg(OH)2 is insoluble. Therefore, we have a reaction because there is at least one insoluble product. As so we write a balanced chemical equation. 2KOH (aq) + MgBr2 (aq) ---> 2KBr(aq) + Mg(OH)2(s) --------------------------------------... (NH4)2SO4 + ZnCl2 ---> ??? Predict the two products and check their solubilities in water. Both are soluble. (NH4)2SO4 + ZnCl2 ---> NH4Cl(aq) + ZnSO4(aq) Therefore, there is no insoluble product, and no reaction (NH4)2SO4 + ZnCl2 ---> no reaction --------------------------------------... * If you need to look at the solubility rules, you can find them here http://www.csudh.edu/oliver/chemdata/sol... ========== Follow up ========== I just happened to notice that JohnDx5454 has misidentified the chemical family for ZnSO4. ZnSO4 is zinc sulfate, and is soluble in water. ZnSO4 is not zinc sulfide. Zinc sulfide is ZnS and it is insoluble in water.
How do i know if two aqueous compounds create a precipitate reaction?
Look at the solubility rules. SrS(aq) + CuSO4(aq) --> CuS(s) + SrSO4(s) ..... SrS is only slightly soluble in water Copper(II) sulfide and srontium sulfate are both insoluble in water. 2AgNO3(aq) + CaSO4(aq) --> Ag2SO4(s) + Ca(NO3)2(aq) 3Zn(NO3)2 + (3NH4)3PO4 --> Zn3(PO4)2(s) + 6NH4NO3(aq) The whole point of a double replacement reaction is to "swap" the cations and anions between two compounds to make two new compounds. But this reaction will only occur if one or both of the products are insoluble in water and form a precipitate. The only way to know that is to do it, or to consult the solubility rules.
Need help with a precipitation reaction in chemistry?
Write a balanced equation: For this equation ignore the water of hydration: MgSO4(aq) + Ba(NO3)2 (aq) → BaSO4(s) + Mg(NO3)2(aq) 1mol MgSO4 reacts with 1 mol Ba(NO3)2 to produce 1 mol BaSO4. Mol MgSO4.7H2O in 1.250g of compound Molar mass MgSO4.7H2O = 246.5 g/mol 1.250g = 1.250/246.5 = 0.0050 mol MgSO4.7H2O 1mol MgSO4.7H2O = 1 mol MgSO4 + water Therefore you have 0.0050 mol MgSO4 You require 0.0050 mol Ba(NO3)2 1000mL solution contains 0.200 mol Ba(NO3)2 Volume that contains 0.0050 mol = 1000/0.200*0.005 = 25mL You will require 25.0mL of the Ba(NO3)2 solution.
Two compounds, A and B, have the formula of C3H6O. Determine their condensed structural formulas and names....
The C:H:O ratio, and the chemical tests tells you that you you must have a carbonyl in there- if it were an alcohol there would be 2 more hydrogens. So, how many different arrangements of 3 carbon atoms can you get? Only 1: A chain of 3. Somewhere on this chain, resides a carbonyl substituent. The first test shows a reaction with Benedict's soln, but not iodoform. The reaction with Benedict's soln tells you there is a carbonyl present, but it does not react with Iodoform. If it doesn't react with iodoform, there is no C(O)CH3 functionality, as this is what iodoform tests for. So, it cannot be CH3C(O)CH3. Therefore, it must be the aldehyde: CH3CH2C(O)H. The second compound does react with iodoform, so it must in fact be the ketone: CH3C(O)CH3. So, A = propanal, B = propanone
When writing a precipitation reaction equation, how do you know which two elements go together? ?
Omygosh, Hope this doesn't sound too presumptuous, but are you sure the first part is Ag(NO3)3 + Na2S ===>? Silver is usually in the +1 state, so it wouldn't have 3 nitrates. If that is so, then let's work on my assumption -- that it will only have one nitrate. Nitrate has a -1 charge, so the final product with sodium would be sodium nitrate, NaNO3. Since you had two sodiums from Na2S, you'll need 2 NaNO3, which means you'll need two AgNO3. And that all works out, since the siver sulfide will be Ag2S. The total equation is now: 2AgNO3(aq) + Na2S(aq) ---> Ag2S (s) + 2NaNO3. The other guy was right for early chemistry classes -- they usually don't give you problems where things just stand still. But later on they might, or give you more than two reactants -- which do you choose to combine? 1. First, if they are all soluble (sometimes happens), they don't really combine anyway -- they stay in their dissociated state (in the above equation, you would actually have 2Na+(aq) + 2NO3-(aq) on the right) 2. If something precipitates, there are a few you can actually memorize, like AgCl, CaCO3, etc. Usually your text book will have a table of Ksp's (sometimes in the back, sometimes just in the chapter on solubility). If that's the case, look at that table and if the compound turns up, that will be at least one combination (see reference below -- Ksp for Ag2S is 10^-49; VERY insoluble). Hope this helped!
A short precipitation reaction question.?
"AgNO3 and NH4NO3 (silver nitrate and ammonium nitrate) are both colorless. How would you distinguish between the two solutions?" I know that both of these compounds are soluble, but the Ag could possibly form a solid in a precipitation reaction, I think. So, couldn't you just use any arbitrary insoluble compound and make a precipitation reaction with each of the two soluble compounds I mentioned?