1 / 25

Semester 1 Chemistry Review

Semester 1 Chemistry Review. DAY 2. Formula Weight. Find the formula weight of aluminum sulfate. Al 2 (SO 4 ) 3 Al - 2 x 26.98 = 53.96 S - 3 x 32.06 = 96.18 O - 12 x 16.00 = 192.00 + TOTAL 342.14 amu. Percent Composition.

ryder
Télécharger la présentation

Semester 1 Chemistry Review

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Semester 1 Chemistry Review DAY 2

  2. Formula Weight Find the formula weight of aluminum sulfate. • Al2(SO4)3 • Al - 2 x 26.98 = 53.96 • S - 3 x 32.06 = 96.18 • O - 12 x 16.00 = 192.00 + • TOTAL 342.14 amu

  3. Percent Composition • What is the percent composition of Aluminum, Sulfur, and Oxygen in Aluminum Sulfate? • Al - 2 x 26.98 = 53.96 / 342.14 x 100 • S - 3 x 32.06 = 96.18 / 342.14 x 100 • O - 12 x 16.00 = 192.00 / 342.14 x 100 • TOTAL 342.14 amu

  4. Answers Al2(SO4)3 is: 15.77 % Aluminum 28.11 % Sulfur 56.12 % Oxygen

  5. Mole Conversions • A mole is 6.02 x 1023 of anything. • There are 6.02 x 1023 amus in 1 gram. • 53.2 grams of aluminum sulfate is how many moles?

  6. Grams to Moles • 7.2 moles of Aluminum Sulfate is how many grams.

  7. Empirical vs. Molecular Formulas • Empirical Formulas are formulas whose subscripts are in their lowest terms. • Examples: Anything Ionic - Na2SO4 or CO2 or CH2O

  8. Molecular Formula • For ionic compounds, their molecular formula is the same as their empirical formula. • Some covalent molecules have molecular formulas that can be reduced to empirical formulas. • Examples - C6H12O6 or N2O4

  9. O - 47.04% Ca - 29.40% S - 23.56% = 2.94 = .7335 = .7349 O-4 Ca-1 S-1 Answer : CaSO4 What is the empirical formula for a compound made up of:

  10. Chemical Reactions Equations show: • 1. the reactants which enter into a reaction. • 2. the products which are formed by the reaction. • 3. the amounts of each substance used and each substance produced.

  11. Two important principles to remember: • Every chemical compound has a formula which cannot be altered. • A chemical reaction must account for every atom that is used. This is an application of the Law of Conservation of Matter which states that in a chemical reaction atoms are neither created nor destroyed.

  12. Some things to remember about writing equations: • The diatomic elements when they stand alone are always written: • H2, N2, O2, F2, Cl2, Br2, I2 • Before beginning to balance an equation, check each formula to see that it is correct. NEVER change a formula during the balancing of an equation.

  13. More Things to Remember: • Balancing is done by placing coefficients in front of the formulas to insure the same number of atoms of each element on both sides of the arrow. • The sign, → , means "yields" and shows the direction of the action.

  14. Types of Reactions • Composition • Decomposition • Replacement • Ionic (Double Replacement) • Combustion

  15. Composition Reaction • * two or more elements or compounds may combine to form a more complex compound. • * Basic form: A + X → AX • 2Mg + O2 → 2MgO

  16. Decomposition: • * A single compound breaks down into its component parts or simpler compounds. • * Basic form: AX → A + X

  17. 4 Types of Decomposition RXNS • 2 element decomposition • 2HgO → 2Hg + O2 • Metallic chlorates, • decompose into • metallic chlorides and oxygen. • 2KClO3 → 2KCl + 3O2

  18. Metallic carbonates, when heated, form metallic oxides and CO2. • CaCO3 → CaO + CO2 • Most metallic hydroxides, when heated, decompose into metallic oxides and water. • Ca(OH)2 → CaO + H2O

  19. (Single) Replacement • Replacement of a metal in a compound by a more active metal. • Fe + CuSO4 →FeSO4 + Cu • Replacement of nonmetals by more active nonmetals. • Cl2 + 2NaBr →2NaCl + Br2

  20. Ionic (Double Replacement) • NaCl + AgNO3 → • NaNO3 + AgCl • HCl + NaOH → • NaCl + H2O

  21. Combustion • Hydrocarbon + Oxygen • (CxHy) + O2 → CO2 + H2O • (CxHy) + O2 → CO + H2O

  22. Grams / Moles / Atoms • Grams A Moles A Atoms A • Grams B Moles B Atoms B

  23. Limiting Reagent Problems • 52.0g of hydrochloric acid react with 63.2 g of zinc. • What is the limiting reagent? • How much product is formed? • How much excess remains?

  24. 2HCl + Zn ---> ZnCl2 + H2 • 52.0g HCl • 63.2g Zn • 52.0g HCl

  25. 52.0g HCl 63.2g Zn 52.0g HCl = 1.44 g H2 = 1.95 g H2 = 97.2 g ZnCl2 2HCl + Zn ---> ZnCl2 + H2

More Related