How To Find Potassium Dichromate And Sodium Sulfite

Posted by on April 24, 2012

James asks…

Help with an equation?

what is the net ionic equation for “Potassium dichromate is added to an acidified solution of sodium sulfite“? I’m confused because both potassium sulfite and sodium dichromate are soluble.

answers:

It’s a redox equation. Here’s the unbalanced net ionic:

H^+ + Cr2O7^2+ + SO3^2- —> Cr^3+ + SO4^2- + H2O

Here’s more on redox:

http://www.chemteam.info/Redox/Redox.html

Donna asks…

How to predict the Reactants and products?

Potassium dichromate solution is added to an acidified solution of sodium sulfite. How do I predict the reactants and produts and eliminate the spectator ions? Also, is this reaction acidic or basic?

answers:

Use the Lavoisier’s problems solving method

William asks…

what are the products of this reaction?

Lithium metal is burned in air.

gaseous hydrofluoric acid (HF) reacts with solid silicon dioxide.

and potassium dichromate added to acidified solution of sodium sulfite?

these are so tricky, i cant predict the correct answer.

answers:

Hi Kitty! Dr. J to the rescue with a full answer.

1) 4Li + O2 —> 2Li2O

2) 4HF + SiO2 —> SiF4 + 2H2O

3) It is simpler if we eliminate the K and the sodium and write the equation ionic because it is a redox reaction and we need to balance.

The overall redox equation will be:

Cr2O7(=) + SO3(=) + H(+) —> Cr(+3) + SO4(=).

Now you balance by the half reaction method. The two reactions are:

6e(-) + Cr2O7(=) + 14H(+) —> 2Cr(+3) + 7H2O
3SO3(=) + 3H2O —> 3SO4(=) + 6H(+) + 6e(-)

Eliminating the electrons:

Cr2O7(=) + 3SO3(=) + 8H(+) —> 2Cr(+3) + 3SO4(=) + 4H2O

This one was tough!!! Thumbs up!

If you want you could put the K and the Na back.

Best answer?

Donald asks…

can someone check my chemistry homework!!!!?

topic is polyatomic ions

compound / formula & charge

lithium + phosphate/ Li3PO4 – um i just notice something. would this be Li^3PO4 instead?
Barium + cyanide/ Ba(CN)2
Potassium + Perchlorate/ KClO4
sodium + Nitrate/ NaNo3
Beryllium + hydroxide/ Be(OH)2
potassium + dichromate/ need help
calcium + sulfite/ need help
ammonium + sulfate/ need help

i understand how to do this but i get a little confuse about the ( ) like when to use them. and which number goes up or down.

answers:

Potassium + dichromate/ need help
calcium + sulfite/ need help
ammonium + sulfate/ need help
K has +1 charge, Dichromate = Cr2O7^-2 (-2charge)
Ca has +2 charge, Sulfite = S^-2 (-2 charge)
Ammonium has +1 charge = NH4^+1 (+1 charge).Sulfate = -2 charge
.
K2Cr2O7 (K^+1, Cr2O7^-2)
CaS….(Ca^+2, S^-2)
(NH4)2SO4

The number up or down problem is just like math with exponents
x^2 is x squared.
.
In chemistry, the charge is written as an exponent. Mg is in the 2nd column of the periodic table, so it has a charge of +2, written as Mg^+2
.
The subscript tells you the number of the atoms or ions that are in the compound.
In MgCl2, there are 2 Cl ions.
.
In the phosphate ion, PO4^-3, the 4 should be a subscript. Magnesium phosphate should be written as Mg3(PO4)2; because the charges have to be balanced. In Mg^+2 PO4^-3 you need to have a +6 and -6 charge to have the charges balanced. What I really mean is the total charge must equal 0. Yahoo will not let me make the 2, 3, and 4 subscripts. I wish the key board had an upside down ^.
.
You will notice that I used parenthesis around the PO4.
.
If an ion is polyatomic, use parenthesis.
.
You only write charges on an ion when you are in the process of balancing the charges. After that step is finished, no charges are written, it gets too messy.
Here are some examples
Mg^=2..Cl^-1…balance charges..MgCl2…(2 is a subscript)

Mg^2…ClO3^-1…balance charges…Mg(CLO3)2, not MgClO32. This compound does not have 32 O atoms!!

NH4^+1…PO4^-3….Balance charges. (NH4)3PO4, not NH43PO4 (the 4,3,and 4 are subscripts) Ammonium Phosphate does not have 43 H’s.

Linda asks…

Are my chemistry reactions right?

1.) Lithium metal is burned in air.
4Li + O2 –> 2Li2O

2.) Aluminum metal is added to a solution of copper(II) chloride
2Al + 3CuCl2 –> 3Cu + 2AlCl3

3.) Manganese(II) nitrate solution is mixed with sodium hydroxide solution
Mn(NO3)2 + NaOH –> 2NaNO3 + Mn(OH)2

4.)Gaseous hydrofluoric acid reacts with solid silicon dioxide
4HF + SiO2 –> 2H2O + SiF4

5.) The hydrocarbon hexane is burned in excess oxygen
2C6H14 + 7O2 –> 6CO2 + 14H20

6.) Equal volumes of dilute equimolar solutions of sodium carbonate and hydrochloric acid are mixed.
Na2CO3 + 2HCl –> H2CO3 + 2NaCl

7.) Potassium dichromate solution is added to an acidified solution of sodium sulfite.
*I don’t know how to do this one.

8.) A sample of calcium carbonate is heated.
CaCO3 –>
*I don’t know if the products would be Ca2+ and CO32- ; or if it would be CaO and CO2

Any help is appreciated, and I thank you in advance for your time.

answers:

Mn(NO3)2 + 2 NaOH = 2 NaNO3 + Mn(OH)2

2 C6H14 + 15 O2 = 6 CO2 + 14 H2O

Na2CO3 + HCl = NaCl + NaHCO3

8 H+ + Cr2O72- + 3 H2SO3 = 2 Cr3+ + 3 H2SO4+ 4 H2O

CaCO3 = CaO + CO2

Powered by Yahoo! Answers

Leave a Reply

Your email address will not be published. Required fields are marked *

*

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>