How to Find the Mole

This week in chemistry we learned about the mole including mole-particle relationship, molar mass,mole-mass relationship, mass-particle relationship, percent composition, and empirical formulas. All of this sounds really confusing but its actually pretty easy when you get the hang of it. First, a mole is a unit created by chemists to measure the amount of a substance and 6.02x10^23 particles of a substance.

Mole-particle relationship: To find the mole-particle relationship you have to start with the part that is given to you, use conversion factors so the units cancel, multiply fractions (numerator must be multiplied together and then divided by the product of the denominator), then round your answer to the correct number of sig figs and include the units. Remember 1 mole = 6.02x13^23 particles and use it as your conversion factor.

Molar mass: Molar mass is the massing of 1 mole of a substance. To find the molar mass of an element you must first find the atomic mass of the element on the periodic table. After, add the two masses of the separate elements together to find the total mass of both elements. Always remember to round the molar mass to the hundredths place!

Mole-mass relationship: To find the mole-mass relationship you find the mole mass then use the conversion factor 1 mole = molar mass (g). First write the given information down, then find the molar mass of the elements, put the molar mass over 1 mole and use the conversion to find the mole-mass relationship

Mass-particle relationship: In mass-particle relationship you must decide weather you must use the 1 mole= 6.02x10^23 conversion factor or the 1 mole= molar mass (g). This sounds difficult but its actually pretty easy if you just think about what units you need to cancel out.

Percent Composition: To find the percent composition the conversion factor you want to use is %composition= mass of element over mass of compound x 100%. Do this separate for each element to get the individual percent composition. Always round the percentages to the tenths place.

Empirical formulas: An empirical formula is the lowest whole number ratio of the atoms of each element in the compound. Remember that formula units are always found in "reduced" form. For example H2O2 would be HO.

Molecular Formulas: The molecular formula of a compound is either the same as its empirical formula or it is a simple whole number multiple of the empirical formula. To find the Molecular formulas first calculate the empirical formula mass, then divide the molar mass by EFM, lastly multiply all subscripts of the empirical formula by the answer to step two.

Hydrate Lab: The hydrate lab was a fun lab to do in class and it was fairly easy. A hydrate is a solid ionic compound in which water molecules are trapped. In the lab we had to first figure out the formula for copper sulfate pentahydrate. After that we calculated the mass of the copper sulfate pentahydrate which came to be .704g. We transfers the hydrate to the test tube and heated the test tube till all the water was gone from the hydrate. Our experiment was a sucsess because we lost the correct amount of water to loose .004g of water.
  
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