If you have 12 moles of a substance, how many molecules do you have of that substance? Suppose the substance has a molecular weight of 342. How many grams of that substance would you have to dissolve in a liter of water to make a 12 M solution?

each mole contains avagradro's number of molecules.

massingrams=molmass*Molarity*volumeinliters

To determine the number of molecules in 12 moles of a substance, we can use Avogadro's number, which is approximately 6.022 x 10^23 molecules per mole. So, to calculate the number of molecules, simply multiply the number of moles by Avogadro's number:

Number of molecules = 12 moles x (6.022 x 10^23 molecules/mole)

Next, let's calculate the number of molecules using the given molecular weight of 342 grams/mole. We can use this information to convert the given grams into moles, and then use Avogadro's number to find the number of molecules:

1 mole of a substance = molecular weight in grams

So, the number of moles of the substance can be calculated as:

Number of moles = (12 moles) x (342 grams/mole)

Now, let's determine the grams of the substance required to make a 12 M (molar) solution in 1 liter of water. A 12 M solution means that there are 12 moles of the substance dissolved in 1 liter of water.

To calculate the grams needed, we use the formula:

Grams = (Number of moles) x (molecular weight)

Grams = (12 moles) x (342 grams/mole)

Therefore, to make a 12 M solution in 1 liter of water, you would need to dissolve 4,104 grams of the substance.