Chemistry from A-Z - Home



Name: ____________________ Defining Percent Composition Using Paper Clips-5772152476500Percent composition is used to find the percentage by mass of elements in a compound. Imagine the bag of paper clips represents formula of a particular compound. The different designs of the clips will represent the different elements that make up this compound. The repetition of the same design will represent the number of atoms for that particular element in the compound. In this activity, you will use your bag of paper clips to determine the percent by mass of each type of paper clip in sample.Do Now: 5594985-127000Go to your assigned lab table and make sure you have the following items:A bag containing a mixture of different types of paper clips.An electronic scaleCalculatorReference tablesBrainstorm with your lab partner and devise a plan to determine the percent by mass of each type of paper clip in your bag. Briefly describe your and your partner’s procedure in the box below.-4629151371600Create a table summarizing your results-4629151308100If all the paper clips represented atoms that are part of a chemical formula, create a formula that could possibly represent one molecule in your bag. (Create a Key using letters to represent each type of paper clip.)10858510477500For example: =A______________________________What Does the Percent Composition of a Compound Tell You?12515859779000Using Table T, in your reference tables, write out the formula for calculating percent composition.5086351143000 2. Potassium chromate, K2CrO4, is used in textile industry to tan leather and dye fabrics.-571584455% K = ___________ % Cr = ____________ % O = ____________00% K = ___________ % Cr = ____________ % O = ____________ 5480685231140003. Zinc carbonate (ZnCO3) is used as a zinc supplement in animal feed. What is the percent composition of zinc carbonate?%Zn = __________ , %C = _____________ , %O = _______________4. Allicin (C6H10S2O) is the compound that gives garlic its odor. What is the percent composition of allicin?-46291516065500%C = __________, %H = _________, %S = ____________, %O = _________5. Ethylenediaminetetraacetic acid (EDTA) is used as a food preservative and in the treatment of heavy- metal poisoning. Calculate the percent composition of EDTA.50209455461000C10H16N2O8%C = ________, %H = ________, %N = ________, %O = _________6. Trinitrotoluene (TNT) is a white, crystalline substance that explodes at 2400 C. Calculate the percent composition of each element in TNT, C7H5(NO2)3.51352459398000%C = ________, %H = ________, %N = ________, %O = _________7. Determining the percent composition of water in a hydrate.a. Write out the chemical formula for barium chloride dihydrate.__________________________________-12255532766000b. Determine the percent composition of water in barium chloride dihydrate.-8255565150008. Borax is found in laundry booster, certain hand soaps and in some toothpaste. The chemical formula for borax is Na2B4O7? 10H2O. Determine the percent composition of water in borax.8. What is the percent composition by mass of oxygen in Ca(NO3)2 (gram-formula mass = 164 g/mol)? (1) 9.8% (2) 48% (3) 29% (4) 59%9. Which compound has the greatest percent composition by mass of sulfur? (1) BaS (2) MgS (3) CaS (4) SrS10. Which compound has the highest percent composition by mass of strontium? (1) SrCl2 (2) SrO (3) SrI2 (4) SrS45637451714500010604510985500 ................
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