What mass of chlorine reacts with 20.0g of iron to form iron(III) chloride? →

To use the mass of iron to find the mass of chlorine needed to react in the reaction, we have to find a way to compare them. We can do this using mole. This is because we can easily convert between moles and mass, and compare more accurately in moles. Remember, the amount of any substance that contains the same number of atoms as 12 g of carbon-12 (which can be found for any substance given the right information).

Find Mole of Iron

Moles Iron = mass ÷ molar mass

                 =  20.0g ÷ 55.84 g/mol

                 =  0.3582 moles

Determine Moles of Chlorine (Mole Ratio)

Based on the balanced equation, the mole ratio of Chlorine to Iron is 3 to 2. Therefore in the reaction, there are ³/₂ more moles of chlorine than iron.

⇒ since moles of iron =  0.3582 moles

   then moles of chlorine =  0.3582 moles × ³/₂

                                          = 0.5372

Find Mass of Chlorine

Mass chlorine = molar mass × moles

                        = 70.90 g/mol ×  0.5372 mol

                        = 38.09 g

to make a supersaturated solution, make a saturated solution of sugar by adding 360 grams of sugar to 100 ml of water at 80 degrees celsius. when the water cools back down to 25 degrees, that 360 grams of sugar will still be dissolved even though the water should only dissolve 210 grams of sugar.

"you start with 15.67 g mgco3-xh2o, when heated and all the water is removed, you are left with 7.58 g mgco3 only.

therefore, you had 15.67 - 7.58 = 8.09g h2o  

moles of each :

7.58g mgco3 = ? moles = 7.58g / 83.4g/mole = 0.09moles  

8 09g h2o = ? moles = 8.09g / 18g/mole = 0.44moles  

molar ratio between the two by dividing both numbers by the smallest number :

0.09 / 0.09 = 1  

0.44 / 0.09 = 4.8  

mgco3-5h2o"