chem help !!!

[Carah.khan]

i need help in solving this moles question .

Sodium reacts with water asfollows:
2Na(s)+2H2O(l)=2NaOH(aq)+H2(g)
1.15g of sodium is allowed to react completely with water.the resulting solution is diluted to 250cm3.calculate the concentration in mol /dm3 of the resulting hydroxide solution .

 

[Zuhsid]

i need help in solving this moles question .

Sodium reacts with water asfollows:
2Na(s)+2H2O(l)=2NaOH(aq)+H2(g)
1.15g of sodium is allowed to react completely with water.the resulting solution is diluted to 250cm3.calculate the concentration in mol /dm3 of the resulting hydroxide solution .

-Convert 1.15g into moles: (1.15/23)=0.05

-By ratio method, see how many moles of NaOH are formed:
2:2
0.05:x
So it forms 0.05 moles too....

-Moles=concentration * Volume
Concentration= Moles/Volume
Concentration=0.05/(250/1000) -----> In the denominator, i have converted cm3 into dm3
Concentration= 0.2 mol/dm3

 

[Carah.khan]

-Convert 1.15g into moles: (1.15/23)=0.05

-By ratio method, see how many moles of NaOH are formed:
2:2
0.05:x
So it forms 0.05 moles too....

-Moles=concentration * Volume
Concentration= Moles/Volume
Concentration=0.05/(250/1000) -----> In the denominator, i have converted cm3 into dm3
Concentration= 0.2 mol/dm3

thanx

 

[Carah.khan]

And this one too plz
-3. +
Aqueous XO ions form a precipitate with aquous silver ions Ag .
4
a)write a balanced equation for the reaction,including state symbols
-3
b)when 41.18cm3 of a solution of aqueous silver ions with a concentration of 0.2040 mol /dm3 is added to a solution of XO ions,1.72g of the 4
precipitate is formed.
i)Calculate the amount (in moles) of Ag+ ions used in the reaction.
ii)Calculate the amount (in moles) of the precipitate formed.
iii)calulate the molar mass of the precipitate.
iv)Determine the relative attomicmass of X and identify the element .

Plzzzzzzzzzzzzzzzzzzzzzz this is urgent

 

[Carah.khan]

the ions are :
Ag+
-3
XO
4

 

[Zuhsid]

the ions are :
Ag+
-3
XO
4

What is 3 and 4 in this???

 

[Carah.khan]

What is 3 and 4 in this???

there is a problem while posting so the ions become confusing.
-3 is the oxidation state of this ion XO and 4 is the number below O

 

[Zuhsid]

A). (XO ion) + 3(Ag+ ion) = Ag3XO4 --------> in the resulting ion, both 3 and 4 aur number of ions written as smaller numbers, and the state symbol with both the ions are (aq) and the resulting compound has a state symbol of (s)

B).
I) moles = concentration * volume
= 0.2040 * 0.04118

Ii) to do this, use the ratio method like I did in the question I solved before, using the equation formed in the first part...."

Iii) then using the formulae: moles=mass/molar mass
Calculate the molar mass, where moles is answer of part Ii) and mass is 1.72

Iv) once you find the molar mass, from it, subtract the mass of 3 Silver(Ag) ions), then use the resulting answer to see as to which element the mass belongs to in the periodic table.....and see what the element is and it's atomic number....

 

[Zuhsid]

And this one too plz
-3. +
Aqueous XO ions form a precipitate with aquous silver ions Ag .
4
a)write a balanced equation for the reaction,including state symbols
-3
b)when 41.18cm3 of a solution of aqueous silver ions with a concentration of 0.2040 mol /dm3 is added to a solution of XO ions,1.72g of the 4
precipitate is formed.
i)Calculate the amount (in moles) of Ag+ ions used in the reaction.
ii)Calculate the amount (in moles) of the precipitate formed.
iii)calulate the molar mass of the precipitate.
iv)Determine the relative attomicmass of X and identify the element .

Plzzzzzzzzzzzzzzzzzzzzzz this is urgent

In the answer I ignored the *4* you used after writing the mass of the precipitate in part B...... Was that a mistake?

 

[Zuhsid]

A). (XO ion) + 3(Ag+ ion) = Ag3XO4 --------> in the resulting ion, both 3 and 4 aur number of ions written as smaller numbers, and the state symbol with both the ions are (aq) and the resulting compound has a state symbol of (s)

B).
I) moles = concentration * volume
= 0.2040 * 0.04118

Ii) to do this, use the ratio method like I did in the question I solved before, using the equation formed in the first part...."

Iii) then using the formulae: moles=mass/molar mass
Calculate the molar mass, where moles is answer of part Ii) and mass is 1.72

Iv) once you find the molar mass, from it, subtract the mass of 3 Silver(Ag) ions), then use the resulting answer to see as to which element the mass belongs to in the periodic table.....and see what the element is and it's atomic number....

In the last part, you also have to subtract the mass of 4 oxygen ......