# Chemistry homework

1. Sep 27, 2007

### LasPapito

Can anyone please help me to do my homework, i just don't get it?

1.Write the equations of dissociation of Carbonic acid, sodium carbonate and sodium hydrogen

2.Write molecular and net ionic equation of H3PO4+Ba(OH)2

3.800ml of water been added to 200ml 40% phosphoric acid solution (d=1,3g/cm3). What is the percentage conc. of the prepared solution?

4.What is molar conc. of 40% H3PO4 solution? (d=1,3g/cm3)

And i would be really thankful if you would show me how exactly to get the answer

2. Sep 27, 2007

### chemisttree

Sorry, can't help until you give it your best effort.

3. Sep 27, 2007

### LasPapito

CO2+H2O⇌2H+co3
2Na+O+CO2⇌2na+co3
Na+OH+2H+CO3⇌Na+HCO3+H2O

2H3PO4+3Ba(OH)2->Ba3(PO4)2+6H2O
6H+2PO4+3BaOH->Ba3(PO4)2+6H2O

Thats how much i managed to do.. I'll couldn't do 3 and 4 parts, i just don't get it... :/

Last edited: Sep 27, 2007
4. Sep 27, 2007

### Vagrant

For the first part write the charges of ionic species.

5. Sep 27, 2007

### Gokul43201

Staff Emeritus
Are you missing something at the end there? There's no such thing as "sodium hydrogen".

On the left side of each dissociation equation, you need to have the formula of the compound that's dissociating.

Example: $Na_2CO_3 \longrightarrow ... + ...$

6. Sep 27, 2007

### LasPapito

im sry.. Sodium hydrogen carbonate.. after your example i managed to do two first equations, but i don't know how to make the 3rd one.. there is 3 elements, NaHCO3.. :/

7. Sep 27, 2007

### LasPapito

is this correct:
2H3PO4+3Ba(OH)2->Ba3(PO4)2+6H2O
2H3PO4+3Ba(2+)+2OH(-)->Ba3(PO4)2+6H2O ?

8. Sep 28, 2007

### chemisttree

Well, if I were writing the net ionic equation for the reaction between sulfuric acid and barium hydroxide, I would write:

$$2H^+ + SO_4^{-2} + Ba^{+2} + 2(OH^-) \rightarrow{} 2H_2O + BaSO_4 (s)$$

and the molecular reaction would be:

$$H_2SO_4 + Ba(OH)_2 ------> 2H_2O + BaSO_4$$

Last edited: Sep 28, 2007