Calculate the molarity of a solution prepared by dissolving 12.5 g of Na2CrO4 in enough water to produce a solution with a volume of 810. mL .

0.0953M

Explanation:

First, let us calculate the number of mole present in 12.5g of Na2CrO4.

Molar Mass of Na2CrO4 = (23x2) + 52 +(16x4) = 46 + 52 +64 = 162g/mol

Mass of Na2CrO4 = 12.5g

Number of mole =?

Number of mole =Mass /Molar Mass

mole of Na2CrO4 = 12.5/162 = 0.0772mol

Now, we can calculate for the molarity as follows:

Mole = 0.0772mol

Volume = 810mL = 810/1000 = 0.81L

Molarity =?

Molarity = mole /Volume

Molarity = 0.0772mol/0.81L

Molarity = 0.0953M

2b2t

explanation:

2b2t

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.