Presentation on theme: "Solve Chemistry Math Problems"— Presentation transcript:
1Solve Chemistry Math Problems “When in doubt, go to moles.”
2Use Dimensional Analysis Analyze the labelsChange them with converting fractionsDo the “number math” last (after all the labels cross off so they are the same on both sides of your equation.)
31: Identify your goal unit: What label goes with the number you want to find?Is it grams, moles, liters, joules, or some other unit?Is it a combined unit, like moles/liter, or cal/(gram*Celsius)?
42. Write the labelWrite an = sign, and leave a space for the answer number on the far right side of your paper.Then write the label you want with your answer.
53. Choose a number to convert Choose one of the numbers you’re given, based on its similarity to the goal unit. On the far left side of your paper, write that number as a two line, flat fraction.
64. Convert units multiply by two line, flat fractions Cross out any unit label you find on both the top line and the bottom line.Continue adding converting fractions and crossing out labels.The top must equal the bottom.Memorize the common converting fractions.When all the labels left before the equals sign match the labels after the equals sign, you’re almost finished.
76. Multiply then divideMultiply all the numbers across the top line of your two line fractions.Then divide that answer by each of the numbers across the bottom.Write the result before the goal label on the right.
8Common converting fractions Atomic mass, formula mass:X grams = 1 moleSTP liters of any gas:22.4 Liters = 1 moleAvogadro’s Number:6.02X1023 particles = 1 mole
9Gas Equations Dalton’s Law of Partial Pressures: P1 + P2 + P3 … = PtotalCombined Gas Law:P1V1T2 = P2V2T1 (T must be Kelvin)Ideal Gas Law:PV = nRT
10SolutionsMolarity = MM = moles of solute / Liter of solution
11Heat and Energy Specific Heat : changing temperature # calories/gramoC Heat of fusion: melting or freezing#Joules/moleHeat of vaporization: boiling or condensing# Joules/mole
12Units Moles Grams Liters Energy: calories or Joules Temperature: Kelvin, Celsius, FahrenheitPressure: Atmospheres, Torr, mm Hg, KiloPascalsParticles (atoms, ions, electrons, molecules, formula units…)
13Prefixes Use these as converting fractions, too. Mega = M = 106 Kilo = K = 103centi = c = 10-2milli = m = 10-3micro = “mu” (Greek letter) = 10-6
14Liters of A Liters of B Grams of A Moles of A Moles of B Grams of B X RatioLiters of BX RatioX22.41/22.4X22.41/22.4Grams of AMoles of AMoles of BMole/GramsGrams of BX RatioGrams/MoleX RatioGrams/MoleMole/Grams1/6.021023X6.0210231/6.021023X6.021023Particles of AX RatioParticles of BX RatioMole Map
15Learn the systemDimensional analysis is a procedure you can use to solve most problems.It’s not just for chemistry.You will be given many equations on the SOL test.You still need to memorize some equations.