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Chemistry Mid-term Review

Chemistry Mid-term Review. Ch. 10, 11,13,14, and 15. Material You Should Review. From Last Year! Sig figs Types of Mixtures Exothermic vs. Endothermic Theories of the Structure of the Atom Emission Spectrum Orbitals Trends of the Periodic Table Valence electrons

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Chemistry Mid-term Review

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  1. Chemistry Mid-term Review Ch. 10, 11,13,14, and 15

  2. Material You Should Review From Last Year! • Sig figs • Types of Mixtures • Exothermic vs. Endothermic • Theories of the Structure of the Atom • Emission Spectrum • Orbitals • Trends of the Periodic Table • Valence electrons • Ionic vs. Covalent Compounds • Compound Naming rules • Percent composition of a compound • Molecular Formulas vs. Structural Formulas • Molecular Structures • Moles/Molecules • Electronegativity • All vocabulary words!!!

  3. Material You Should Review From This Year! • Solubility/Properties of Solutions • Types of Solutions • Gas Laws/ Vapor Pressure • What are Acids/Bases/Conjugate Acids/Bases • Calculate pH and pOH/calculate [H+] and [OH-] • Titrations • Kinetic Energy • Phases change vocabulary • Kelvin scale • Molarity • Reading Phase Diagrams • Acid-Base Reactions • All Vocabulary words!!!

  4. CH. 10- Kinetic Energy • What is the Kinetic Theory of Matter? • Matter is made of particles • Particles have Brownian motion 布朗运动 (constant, rapid, and random movement) • Collisions of particles are perfectly elastic (complete transfer of energy) • What is the difference between a crystalline and amorphous solid? Crystalline solids have a crystal lattice with repeating 3D patterns. Amorphous have no lattice and random order • What is atmospheric pressure? Pressure of gas molecules all objects in the Earth’s atmosphere experience. 1 atm = 760mmHg= 14.7 psi= 101.3 kPa

  5. CH. 10- Kinetic Energy • Why do we use Kelvin when dealing with gases? Kelvin directly relates the motion of the particles which produces the pressure of the gas. • What is vapor pressure? How does it relate to the boiling point of a liquid? Pressure produced by a vapor as a liquid changes to a gas. When vapor pressure and atmospheric pressure are equal, a liquid will boil. • What is the heat of fusion? What is the heat of vaporization? Heat of fusion- amount of every needed to melt 1kg of substance Heat of evaporation- amount of energy needed to vaporize 1kg of substance

  6. CH. 10- Kinetic Energy • Label this diagram: Boiling Point Gas Condensation Evaporation Freezing Liquid Melting Melting point Solid

  7. Ch. 11- Gas Laws • Explain: • Boyle’s Law: • Charles’ Law: • Gay-Lussacs’ Law: • Combined Gas Law: • Ideal Gas Law: • Avogadro’s Gas Principle: • Dalton’s Law of Partial Pressures: V1P1=V2P2; Volume and Pressure are inversely proportionate V1/T1=V2/T2; Volume and Temperature are directly proportionate P1/T1=P2/T2; Pressure and Temperature are directly proportionate V1P1/T1= V2P2/T2 PV=nRT; connection between molar concentration of an ideal gas and its V, P, and T. V1n1=V2n2; Moles of gas and the volume of the gas are directly proportionate Ptotal=P1+P2+P3+…; total pressure is equal to sum of all none reactive gases

  8. CH. 11- Gas Laws V2 = V1T2/T1= (10.0L x 423K)/298K = 14.2L V2 = P1V1/P2 = (0.66atm x 3.0L)/5.0 atm = 0.40 L P2=P1T2/T1=(475.0 mmHg x 358K)/312K =546 mmHg

  9. Ch. 11- Gas Laws V2= P1V1T2/P2T1= (1.77 atm x 2.00L x 324K)/(4.01 atm x 303K) V2= 0.944L n=(75 atm)(14.0L)/(0.08206 L atm/ mol K)(295K) n= 43 mol of NO2

  10. Ch. 13- Water and Solutions At 4oC the water molecules are their most dense but as the temperature lowers the H-bonds form hexagonal shapes which forces water to expand as it freezes. This results in ice be less dense than water. • What happens to water at 4oC and at temps lower than 4oC? • Name 3 physical properties caused by H-bonds formed between water molecules • What are the 3 types of solutions that can be produced with increasing solute concentration and solvent temperature? Adhesion- water molecules sticking to surfaces Cohesion- water molecules sticking to each other Surface tension- water molecule resistant force on its surface High specific heat- water can absorb a lot of energy and releases it slowly Unsaturated- still able to dissolve solute in the solvent Saturated- maximum amount of solute within the solvent Supersaturated- raising the temperature allows for extra amounts of solute to dissolve in the solvent; crystalizes when cooled

  11. Ch. 13- Water and Solutions M= 0.6784 molNaCl/ 4.5 L H2O M= 0.15 mol/L = 0.15 M 977.6 mL H2O 1 L H2O 3 molKBr 119.0 g KBr = 349 g KBr 1molKBr 1000 mL H2O 1 L H2O

  12. Ch. 13- Water and Solutions • What is the difference between a solution, a colloid, and a suspension? • What is the Tyndall effect? • How can looking at the structure of a solute and solvent tell you if they will dissolve into each other? Solution- solute completely dissolved; light pass through Colloid- solute completely dissolved; light scatters Suspension- solute separates over time; often reflects light Light photons passing through a colloid collide with particles in the solution and scatter in random directions causing the colloid to glow Using the “Like dissolves Like” rule, a non-polar molecules dissolve into non-polar substances and polar molecules dissolve into polar substances

  13. Ch. 13- Water and Solutions • Explain how solutes effect the boiling and freezing points of a solution • What is an electrolyte? Solutes dissolved in the solvent take up space between the solvent molecules. When the solution is boiling, the solute particles take up space on the surface of the solution which lowers the vapor pressure, so more energy (higher temp) is needed to boil the solution. When freezing the solutes take up space between the solvent molecules and prevent them from moving close together, so more energy (lower temp) must be removed to freeze the solution A solution containing dissolved ions which will allow the passing of electrons through the medium. The more ions present the easier it is for the electricity to pass through the solution.

  14. Ch. 14- Acids and Bases • What is ionization? • How can you tell is a substance is an acid or base? • SO3 and ZnO produce either an acid or a base when mixed with water. Which does each produce? What is the term for compounds that do this? Breaking a covalent compound into ions. Happens with acids dissociating in solution Acids produce hydronium ions (H+) in water while bases produce hydroxide ions (OH-) in water. Acids give off H+ while bases take H+ SO3 (non-metal oxide) when mixed with water produces an acid (H2SO4) so it is an acidic anhydride ZnO (metal oxide) when mixed with water produces a base (ZnOH) so it is a basic anhydride

  15. Ch. 14- Acids and Bases • What is the difference between a strong and weak acid/base? • What is the equation for calculating pH? pOH? • How do scientists monitor the change in pH when doing reactions? Strong acids/bases dissociate completely in solution but weak acids/bases only dissociate a little pH= -log[H+] pOH= -log[OH-] pH + pOH = 14 pH indicators are used to monitor pH changes Litmus paper can tell you if you have an acid or a base and liquid indicators that work in certain pH ranges will tell more specifically what your pH might be.

  16. Ch. 14- Acids and Bases • What is the [OH-] of a solution whose pOH = 2.86 ? • What is the pH of a solution whose [H+] is 2.75 x 10-4 M? • What is the [OH-] of a solution whose pH = 5.43 ? • What is the pH of a 0.0001-M solution of NaOH? [OH- = 10-2.86 = 1.38 x 10-3 M pH = -log[2.75 x10-4] = 3.64 pOH= 14- 5.43= 8.57; [OH-] = 10-8.57= 2.69 x 10-9 M 0.0001 M NaOH = 0.0001 [OH-] pOH= -log [0.0001] = 4 pH= 14-4 = 10

  17. Ch. 15 Acid-Base Reactions • What are the reactants and products of a neutralization reaction? • What is the net iconic equation of reacting KOH and HCl? • What acid-base reaction end with a slightly basic solution? Why? Acid + Base A Salt + H2O HCl + NaOHNaCl + H2O KOH + HCl KCl + H2O OH- + H+ H2O Strong Acid + Weak Base Weak base doesn’t dissociated enough to neutralize all the H+ ions produced by the acid

  18. Ch. 15 Acid-Base Reactions • Label the acid, base, and conjugate acid/base in these reactions: H2O(l)+NH3(aq)NH4+(aq)+OH-(aq) HCl(aq)+H2O(l)H3O+(aq)+Cl-(aq) • What is a buffer? How does it work? Conjugate Acid Base Conjugate Base Acid Acid Base Conjugate Acid Conjugate Base A solution of a weak acid or base and the salt of that same weak acid or base. Solution has compounds that will react with additional H+ and OH- ions so the pH of the solution changes slowly over time

  19. Ch. 15 Acid-Base Reactions An acid‐base titration requires 29.88 mL of 1.17MNaOH to  neutralize5.00 mL of an H2SO4 solution.  Calculate the molarity of theH2SO4 solution. 2 NaOH (aq) + H2SO4 (aq)Na2SO4 (aq) + 2 H2O (l) M1V1=(2)M2V2 M2= (29.88ml)(1.17M)/(2)(5.00ml)= 3.50 M H2SO4 A 20.00‐mL sample of oxalic acid, H2C2O4, solution is titrated with  27.86 mL of 0.250 M KOH solution.  Calculate the molarity of the  H2C2O4 solution. 2 KOH (aq) + H2C2O4 (aq) K2C2O4 (aq) + 2 H2O (l) M1V1=2M2V2 M2= (27.86ml)(0.250M)/(2)(20.00ml)= 0.174 M H2C2O4

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