SnO is a different compound than SnO2. What is the difference regarding the cation?

Sn has a different charge in each of the compounds.

+2, +4 charges, respectively.  

Explanation:

SnO has subscripts of 1, which means it takes only one of each element to make the compound.

We know that oxygen's charge is -2 from the periodic table.

In order for the compound to be neutrally charged,

Sn + O = 0

Sn - 2 = 0.

So, Sn has a +2 charge.

Likewise with the second compound, we know O has a -2 charge.

Sn + 2*(-2) = 0

Sn - 4 = 0

Sn = +4

+2 and +4 are different charges on the Sn cation.  

given:

mass of na = 115 g

excess cl2

to determine:

mass of nacl produced

explanation:

given reaction is-

2na(s) + cl2(g) → 2nacl(s)

since cl2 is in excess, na will be the limiting reagent

as per the reaction stoichiometry na: nacl = 1: 1

i.e. moles of na reacted = moles of nacl formed

now, # moles of na = mass of na/atomic mass

                                  = 115 g/23 g.mol-1 = 5 moles

therefore, moles of nacl = 5

molar mass of nacl = 58 g/mol

mass of nacl = 5 moles * 58 g.mol-1 = 290 g

ans: amount of nacl produced = 290 g