Date: October 2, 2012
HW: % concentration worksheet, formula of a hydrate lab

Today, we learned how to find % concentration of an element in each molecule/compound. To do so the total mass number of each type of element is calculated, then its is divided by the total mass of all elements and multiplied by a hundred.

For example: What is the percentage of each element in an H₂O molecule?                                           
A mole of hydrogen weighs 1g (total 2g since 2 hydrogen atoms are present) and a mole of oxygen weighs 16g , the total is 18g. The percentage of hydrogen 2/18x100= 11.1% and the percentage of oxygen is 16/18x100=88.9%.

We also did a lab: Bubble Gum
Lab goal: The purpose of the lab was to determine the percent sugar present in bubble gum and to write an empirical formula for the bubble gum in the form of  G_xS_y , where G is the fictional symbol for bubble gum (513gram/mole), and a fictional symbol for sugar S (342 grams/mole).

                                                                  
Procedure/data: the mass of the wrapper, bubble gum & wrapper , and chewed bubble gum & wrapper is measured.

Calculations: mass of sugar, mass of the gum before chewing,  mass of gum after chewing, % composition the sugar, and finally the moles of sugar and bubble gum are calculated. The final calculation is equal to the variables in the formula.

Conclusion:

• Claim: what is the empirical formula of the bubble gum?
• Evidence: researchers  have found the ideal formula for the Gum is GS2. How does this compare to your ideal formula.
• Reasoning: If you did not chew the bubble gum fully, how would that effect the empirical formula of your sample.                                          

Next scribe will be Alex S.