ch7 %composition lab
Discussion. The word ‘percent’ means part of a whole, part of one hundred. So, 50 percent means 50 out of 100. Fractions can be expressed as percents. For instance, ½ is 50 percent; ¼ is 25 percent etc. If you divide the part by the whole, and multiply by 100, you can change any number into a percent. So for 1/8, I divide 1 by 8 and get .125; I multiply it by 100, and get 12.5%. 1/8=12.5%.
Gum is made of 2 parts; a part that is soluble- the high fructose corn sweetener(sugar), and a part that is insoluble – what you throw away. Do not put gum without a wrapper on the balance, chewed or unchewed. (if not here, used the bolded data)
Procedure, data, and calculations:
1. Count the boys and girls present in class today. _______(14)boys and ______(10) girls.
The total number of students is _________.
The percent boys is _________ work:
The percent girls is _________ work:
2. a.Weigh your gum, then chew it to remove the sugar, then weigh it again.
My gum before chewing _______(2.95g) My gum after chewing _______ (1.39g) mass of sugar __________
% sugar in my gum_______ work:
From the class data (record your data ) , what would you say is the % sugar in gum?
2. use an evaporating dish, or if they are gone, use a small beaker; b. Weigh e. dish_________ and e. dish with saltwater _______. (use between 8-10mL; record the volume _____mL.) put your initials on the dish with a sharpie, and place it in the appropriate oven overnight. c. The next day mass dish with salt_________, and Calculate % (by mass) of salt in this saltwater;(Find the percent error if the actual value is 22.8 % salt. ) and calculate the density of the saltwater and percent error (if actual density is 1.11g/mL)
Work:
3. Carbon dioxide is the main greenhouse gas made from burning hydrocarbons
Write the formula of carbon dioxide.__________
mass of carbon in carbon dioxide _______ mass of oxygen in carbon dioxide________
Add up the atomic masses of carbon dioxide _____________
The percent of carbon (by mass) in carbon dioxide _________ work:
The percent of oxygen (by mass) in carbon dioxide _________ work:
4. Calculate the % Composition of your assigned compound (your number in class) ; ask another person to check your calculations. ( for example, ammonium sulfate will have 4 answers;
first write the formula (NH4)2SO4
then, find the formula mass;
2N=28.
8H=8
1S=32
4 O= 64
_____ add the masses
total = 132
finally, divide each part by the whole and *100 for percent
N=28/132= 21.2%
H= 8/132= 6.1%
S= 32/132= 24.2%
O=64/132= 48.5%
the percents should add up to about 100% if everything is right
5. Calculate the moles of sugar in your gum if the sugar in gum has the formula C6H12O6 (rchem may skip for now)
6. Find formula of everyone's compound(& prefix name for covalent compounds)
1- iron II phosphate
2 - calcium acetate
3- strontium chlorate
4- cobalt III sulfite
5- vanadium II bicarbonate
6- titanium III nitrite
7- aluminum hydroxide
8- ammonium carbonate
9- aluminum chromate
10- nickel II perchlorate (ClO4-1)
11- potassium hydrogen carbonate (bicarbonate)
12- barium phosphate
13- zinc chlorate
14 - phosphoric acid (hydrogen phosphate)
15 - hydrobromic acid (hydrogen bromide)
16 - sulfurous acid (hydrogen sulfite)
17 - perchloric acid (hydrogen perchlorate) (ClO4-1)
18 - chloric acid (hydrogen chlorate)
19 - hypochlorous acid (hydrogen hypochlorite) (ClO-1)
20 - Nitrogen (V) oxide
21 - Nitrogen (II) oxide
22 - diarsenic pentoxide
23- tetraphosphorus decoxide
24- sulfur(VI) oxide
7. Conclusion:
Find the molecules of sugar in your gum and calculate the number of molecules you could give everyone in the US
Were you surprised by the gum? Why or why not?
What does soluble mean? Insoluble?
Are you the master of percents? Why or why not?
What did you learn from this activity?