A solution contain 25g of Na2Co3in750cm3 of aasolution. Calculate concentration in (1) g/dm3 (2) mol/dm3

25 g x (1000 cm3/750 cm3) = ? g/L = g/dm3.

mols Na2CO3 = grams/molar mass = ?

To calculate the concentration of a solution, you need to know the amount of solute (the substance being dissolved) and the volume of the solution.

In this case, you know that the solution contains 25g of Na2CO3 and the volume of the solution is 750cm3.

(1) To calculate the concentration in g/dm3, you need to convert the volume of the solution from cm3 to dm3. Since 1 dm3 is equal to 1000 cm3, you divide the volume by 1000:
750 cm3 ÷ 1000 = 0.75 dm3

Now, you divide the mass of the solute by the volume of the solution:
25 g ÷ 0.75 dm3 = 33.33 g/dm3

Therefore, the concentration of the solution is 33.33 g/dm3.

(2) To calculate the concentration in mol/dm3, you need to know the molar mass of Na2CO3.

The molar mass of Na2CO3 can be calculated by adding the atomic masses of its constituent elements:
Na (sodium) = 22.99 g/mol
C (carbon) = 12.01 g/mol
O (oxygen) = 16.00 g/mol
3 x O = 3 x 16.00 = 48.00 g/mol
Total molar mass = 2 x Na + C + 3 x O = 2 x 22.99 + 12.01 + 48.00 = 105.99 g/mol

Now, you divide the mass of the solute by the molar mass to get the number of moles:
25 g ÷ 105.99 g/mol = 0.2354 mol

Finally, divide the number of moles by the volume of the solution (in dm3):
0.2354 mol ÷ 0.75 dm3 = 0.314 mol/dm3

Therefore, the concentration of the solution is 0.314 mol/dm3.