Sodium chromate is used to protect iron from corrosion and rusting. determine its formula mass. 261.97 amu 238.98 amu 74.99 amu 161.97 amu 138.98 amu

This problem requires that you know nomenclature, to identify the formula of the compond from its name, and the way how to determine the formula mass once you know formula.

1) Nomenclature: Chromate

Chromate is an ion (anion) from the chromic acid.

Chromic acid is formed from Chromic oxyde with the atomic number 6.

Then Cr + O2 -> Cr2O6 = CrO3

CrO3 + H2O -> H2CrO4

H2CrO4 = 2H(+) + CrO4 (2-) < this is the ion chromate

Now you have to join the chromate ion with the sodium ion => Na2 (CrO4)

2) Now you can calculate the molar mass of the formula Na2(CrO4).

You must only muliply every subscript times the atomic mass of the element:

Na2 => 2 * 23 g/mol = 46 g/mol

Cr => 52 g/mol

O4 => 4 * 16g/mol = 64 g/mol

Formula mass = 46 g/mol + 52 g/mol + 64 g/mol = 162 g/mol

I used the numbers with less significant figures thant the problem required but the answer is evident. Also, g / mol = a.m.u = atomic mass unit.

161.97 a.m.u

Answer : The net ionic equation will be,

Explanation :

In the net ionic equations, we are not include the spectator ions in the equations.

Spectator ions : The ions present on reactant and product side which do not participate in a reactions. The same ions present on both the sides.

The given balanced ionic equation will be,

The ionic equation in separated aqueous solution will be,

In this equation, are the spectator ions.

By removing the spectator ions from the balanced ionic equation, we get the net ionic equation.

The net ionic equation will be,