1.Write the symbol for chromium. What is the atomic number of it in the periodic

ID: 855339 • Letter: 1

Question

1.Write the symbol for chromium. What is the atomic number of it in the periodic table? How many protons and electrons are their in the atom of chromium? Give the highest possible and lowest possible oxidation state for chromium. Determine its molar mass. 2.Na2CrO4. determine the molar mass for this compound and the oxidation state of chromium in it. Write the oxide formula of chromium for the corresponding oxidation state. Determine whether this oxide will react with HCl, NaOH, and write the corresponding reaction equations. 3.Name these compounds: PbS, K2CO3, Cr(NO3)3.

Explanation / Answer

1) symbol cr

atomic number 24

Chromium is element number 24, so a neutral atom would have 24 protons and 24 electrons

The +3 and +6 states are most commonly observed in chromium compounds, whereas the +1, +4 and +5 states are rare.

Molar mass 52 g/mol

2)Molar mass of Na2CrO4 is 161.9732 g/mol

CrO4 adds up to -2
each O is -2

Cr -8 = -2 ===> Cr= +6

chromium (VI) oxide CrO3

yes it will react with hcl and naoh

CrO3 + 6 HCl = CrCl6 + 3 H2O

CrO3 + 2 NaOH = Na2CrO4 + H2O

3)PbS is lead sulfide, lead(II) sulfide and also called as galena

K2CO3 - Potassium carbonate

Chromium(II) Nitrate Cr(NO3)2