How do you determine the formula and molar mass of silver cyanide?

Identify the bond and participating atoms.

Add the of all present.

Formula

You must identify the type of bond(s) present. In this case, it is an ionic compound.

You must also identify the elements/ present. In this case, there is silver (##Ag##), and cyanide (##CN##). - If there was a multivalent element, you have to look at the chemical name. If there are Roman numerals, then the preceding element is multivalent with a charge of whatever the numerals indicate. E.g. ##CuSO_"4"## = Copper (II) sulfate -> the subscripts were reduced.

Knowing that it is an ionic compound, we know that the electrons are transferred. Thus the cation goes first (##Ag##), then the anion (##CN##). The charges are ##1+## and ##1-##, therefore we do not need to reduce.

We get ##AgCN##.

Molar mass

You need a periodic table for this. The molar mass of a compound is simply the sum of all elements in the compound (including the subscripts if any; no coefficients if any).

##Ag## has a atomic mass of ##107.87 mu## ##C## has a atomic mass of ##12.01 mu## ##N## has a atomic mass of ##14.01 mu##

Add them all up and you get ##133.89 g/(mol)##. There is a reason why the units for atomic mass and molar mass are different. Once you learn about mols and such, you will know why, so I will leave that to your teacher.

Hope this helps :)