CHEMISTRY EQUATIONS CHEAT SHEET, Exercises of Chemistry

Download CHEMISTRY EQUATIONS CHEAT SHEET and more Exercises Chemistry in PDF only on Docsity! CHEMISTRY EQUATIONS CHEAT SHEET AUTHOR: JACKSON TAYLOR Gibbs Free Energy Formula: Question: Determine whether the chemical reaction is spontaneous Procedure: 1. Write equation 2. Calculate change in enthalpy ( ) for reaction 3. Calculate change in entropy ( ) for reaction 4. Calculate Gibbs Free Energy ( ) for equation 5. If is positive, the reaction is not spontaneous. If is zero or negative, the reaction is spontaneous Equilibrium Constant Formula: Question: Calculate the equilibrium constant. Procedure: 1. Write a balanced chemical equation 2. Convert moles of gas to concentration if necessary ( ) 3. Draw ICE (Initial, Change, Equilibrium) Table[^1] if necessary 4. Calculate using equation Question: Determine if the system is at equilibrium and, if not, which way it will shift. Procedure: 1. The question will give you a value for (or you might calculate it in a previous section) 2. Use the same procedure as above, but with instead of 3. Compare and : a. If then the system is at equilibrium b. If then the system will proceed in the FORWARD direction c. If then the system will proceed in the REVERSE direction Question: Calculate Procedure: 1. Calculate mole fraction (no of moles/total moles of gas) 2. Multiply mole fraction by total pressure 3. Use equilibrium equation, substituting partial pressures for concentration Question: Given the initial concentration and of a compound, find of the dissociation/hydrolysis of the ions. Procedure: 1. Write the dissociation equation of the compounds (if not already given) 2. Calculate the number of ions from the ( ) 3. Draw ICE Table [^1] with initial concentration as the initial of the compound 4. Substitute the values of each ion (from part 2) in the table as the final equilibrium concentration 5. Write and substitute values 6. Assume the in number is negligible (from equilibrium concentration of compound) and remove 7. Solve. Acid/Base Dissociation Constant Formula: Question: What is the acid/base dissociation constant of {compound}? Procedure: 1. Write the equation for dissociation (reacting with water) 2. Write dissociation expression of the compound 3. Draw ICE table using the initial concentration given, and substitute the other values with 4. Using calcullate the number of or ions, and replace with this value 5. Substitute numbers into dissociation expression Question: Given the concentration and Ka find the pH of the solution. Procedure: 1. Write the equation for the dissociation of compound (react with water) 2. Write dissociation expression of compound[^2] 6. Substitute given Ksp values and concentration of excess reagent (using number of moles from step 3) 7. Solve for concentration of ions Heat of Neutralisation Formula: Question: Calculate the heat of neutralisation of a reaction. 1. Write balanced equation for reaction 2. Calculate number of moles of each reagent to find any limiting reagent 3. If there is limiting reagent, find the new mass that is full volume of limiting reagent + volume of other reagent that reacts (calculate using c=n/v, with n as the moles of limiting reagent) 4. Substitute values into equation c (for water) = 4.18 m (in L if using 4.18, in mL if using 4.18 x 10^3) q in J/mol mass is the amount that is used to react (not the full volume/mass of reagents) q in J/mol Enthalpy of Neutralisation Formula: pH (Power of Hydrogen) Formula: Self-Ionisation Constant Formula: Concentration of or ions (Strong Acids/Bases) Formulae: Question: Calculate the pH of a non-reacting solution (Dilution) Procedure: 1. Calculate number of moles of acid/base 2. Calculate total volume of final solution 3. Calculate the new concentration in moles using combined volumes of mixtures (c = n/v) 4. If acid/base is strong, [H+] = [acid] 5. Calculate pH or pOH using formula Question: Calculate the pH of a reacting solution (Neutralisation) Procedure: 1. Write balanced chemical equation for reaction 2. Calculate number of moles for both reacting solutions 3. Use mole ratios to determine the excess reagent 4. Calculate the number of moles of the excess H or OH ions 5. Find the new concentration in using the combined volume of mixtures (c = n/v) 6. Calculate pH or pOH using formula Heat of Combustion Formula: Question: Calculate the mass of [substance] that must be burnt to increase the temperature of water by [amount]. Procedure: 1. Calculate the heat of neutralisation for water (q = mcat) 2. Sub value into the heat of combustion (h = q/n) to find number of moles 3. Use mole ratios to determine number of moles of ethanol required 4. Convert moles to mass (m = n x MM) Percentage Yield Formula: Percentage Purity Mass of useful product 4 gy Formula: % Purity = “Total mass of sample Percentage lonisation Formula: % Ionisation = iat x 100%