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Synthesis Reactions
Updated 28d ago
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Chapter 4 The Effects of Chemical Reactions. • Introduction to Chemical Reactions. - Chemical reaction: a process in which one or more substances change into one or more new substances. - Clues that a chemical reaction has occurred : 1. Color change Example: two colorless aqueous solutions mix together to produce a bright yellow precipitate. 2. A precipitate (solid) is formed when mixing two solutions together. 3. Gas formation. Bubbles of gas (effervescence) are produced when mixing substances together (solid – liquid or aqueous – aqueous ….) 4. Heat is produced. - Chemical reactions are described by using word equations or chemical equations. - Chemical equations need to be balanced when written because it shows the correct proportions (amounts) of chemicals in a reaction. - A balanced chemical equation has equal number of atoms of each element in the reactants (left hand side) and the products (right hand side). - Exercise: Balance the following equations. a) KClO3→KCl + O2 b) Na2O + H2O NaOH c) Cu + AgNO3 Cu(NO3)2 + Ag d) C3H7OH + O2 CO2 + H2O • Synthesis and Decomposition Reactions. Synthesis: Two or more substances (elements and / or compounds) combine to form one larger compound. General pattern: A + B → C Examples: N2 + 3 H2 → 2 NH3 CaO + CO2 → CaCO3 2 P + 3 Cl2 → 2 PCl3 Decomposition: This is opposite to synthesis; that is, one large compound breaks down (decomposes) into 2 or more simpler substances. Example: 2 KClO3 → 2 KCl + 3 O2 General pattern: R → S + T Remark: Usually decomposition happens due to heat or electricity. - Predicting the product of decomposition or synthesis reactions. 2 AlCl3 (s) → 2 Al (s) + 3 Cl2 (g) Zn (s) + S (s) → ZnS (s) 2 Zn (s) + O2 (g) → 2 ZnO(s) - Single Displacement (Replacement) Reactions. Definition: A reaction in which an element displaces (replaces) another element in a compound, producing a new compound and a new element. General pattern: A + BC → AC + B Example: Mg (s) + CuSO4 (aq) → MgSO4 (aq) + Cu (s) Zn (s) + 2 AgNO3 (aq) → Zn(NO3)2 (aq) + 2 Ag (s) Fe (s) + MgCl2 (aq) → no reaction. Remark: The element that displaces the other element in a compound must be more reactive (active) than that element, otherwise no reaction takes place. In the general pattern above, A should be more reactive than B for the reaction to proceed. The following reactivity (activity) series lists the chemical strength (reactivity) of the metals in order from the more reactive to the less reactive. KPlease stop calling my amazing zebra in the long Nahungry class. sorry !! Ca Mg Al Zn Fe Sn Pb H Cu Ag Examples of single displacement reactions : 2 Al (s) + 3 CuSO4 (aq) → Al2(SO4)3 (aq) + 3 Cu (s) Sn (s) + Zn(NO3)2 (aq) → no reaction Exercise: Complete and balance the following equations. If there is no reaction occurring write no reaction. a) 2 Al (s) + 6 HCl (aq) → 2 AlCl3 (aq) + 3 H2 (g) b) Cu (s) + H2SO4 (aq) → no reaction c) 2 AlCl3 (aq) + 3 Ca (s) → 3 CaCl2 (aq) + 2 Al (s) d) Mg (s) + 2 HNO3 (aq) → Mg(NO3)2 (aq) + H2(g) - Reactivity of halogens decreases down the group. F2> Cl2> Br2> I2 The reactions taking place for the halogens or their compounds are in solution (aqueous) Examples: Cl2 (aq) + 2 KBr (aq) → 2 KCl (aq) + Br2 (l) Cl2 (aq) + NaF (aq) → no reaction. Exercise: F2 (aq) + 2 LiCl (aq) → 2 LiF (aq) + Cl2 (g) I2 (aq) + NaCl (aq) → no reaction • Double displacement reactions. - Definition: A reaction in which two compounds mix together and an exchange of ions (elements) occurs which results in the formation of 2 new compounds. - General pattern: AB + CD → AD + CB - Solubility: the amount of solute that dissolves in a given amount of solvent at a given temperature. - When we say a substance is soluble, it means it dissolves in water; whereas if it is insoluble it means it doesn’t dissolve in water. - The compound in a reaction that is soluble is in aqueous (aq) phase, whereas the compound which is insoluble is in the solid state (s). - The solid which is formed in a double displacement reaction is called the precipitate and it is insoluble. - Solubility rules (used in double displacement reactions). 1. All alkali metal ions and ammonium ion (NH4+) are soluble. 2. All nitrates (NO3-) are soluble. 3. All sulfates (SO4-2) are solubleexceptwith Ba+2 , Pb+2 , Ca+2 , Sr+2 , Ag+ . 4. All chlorides, bromides and iodides(Cl-, Br-, I-) aresolubleexcept with Ag+ , Pb+2 , Hg+, Cu+ 5. All OH- are insolubleexceptwith rule 1, and Ba+2 and Sr+2 . 6. All oxides (O2-), sulfides (S2-), sulfites (SO32-), carbonates (CO32-), phosphates (PO43-) are insoluble except with rule 1 Remark: If all compounds formed in a double displacement reaction are soluble (aqueous) then no reaction takes place. Exercise: State whether each of the following compounds is soluble or insoluble ? Na2SO4 : Fe(NO3)2: LiOH: ZnSO4: PbBr2: BaSO4: Mg(OH)2: PbO: NH4Cl: Na2S: Cu(OH)2: KF: Exercise: Complete and balance the following chemical equations: - KNO3 (aq) + NaCl (aq) → - LiCl (aq) + AgNO3 (aq) → - Zn (s) + FeSO4 (aq) → - NaOH (aq) + CuCl2 (aq) → - ZnCl2 (aq) + Na3PO4 (aq) → - Pb(NO3)2 (aq) + K2S (aq) → • Net ionic equation: a chemical equation which shows ONLY the ions that are involved in the formation of the precipitate (solid). Examples: Pb+2 (aq) + S-2 (aq) → PbS (s) Ag+ (aq) + Cl- (aq) → AgCl (s) Cu+2 (aq) + 2 OH- (aq) → Cu(OH)2 (s) • Full ionic equation: an equation which shows All the ions in the soluble (aqueous compounds) in both reactants and products. Example: - 2 NaOH (aq) + CuCl2 (aq) → 2 NaCl (aq) + Cu(OH)2 (s) 2 Na+ (aq) + 2 OH- (aq) + Cu+2 (aq) + 2 Cl- (aq) → 2 Na+ (aq) + 2 Cl- (aq) + Cu(OH)2 (s) - 3 ZnCl2 (aq) + 2 Na3PO4 (aq) → Zn3(PO4)2 (s) + 6 NaCl (aq) Full ionicequation: 3 Zn+2(aq) + 6 Cl-(aq) + 6 Na+ (aq) + 2 PO4-3 (aq) → Zn3(PO4)2 (s) + 6 Na+ (aq) + 6 Cl- (aq) Net ionic equation: 3 Zn+2 (aq) + 2 PO4-3 (aq) → Zn3(PO4)2 (s) Exercise: Complete and balance the following equation, then write full ionic and net ionic equations for the reaction. Pb(NO3)2 (aq) + 2 NaI (aq) → Full ionic equation: Net ionic equation: Spectator ions: the ions that are not involved in the formation of the precipitate (solid). Note that the spectator ions appear on both sides of the full ionic equation. For example, in the above reaction, Na+ (sodium ions) and NO3- (nitrate ions) are the spectator ions. Exercise: Complete and balance the following equation, then write the net ionic equation and identify the spectator ions. BaCl2 (aq) + K2SO4 (aq) → Net ionic equation: Ba+2 (aq) + SO4-2 (aq) → Spectator ions: - Combustion reaction is a special type of (synthesis) reaction in which the substance reacts with (burns in) oxygen. Examples: C(s) + O2(g) → CO2(g) • Production of gases (lab scale): 1. CO2 2. SO2 3. H2 4. H2S (hydrogen sulfide) 5. NH3 (ammonia) General pattern of the chemical reactions to produce the above gases: 1. Metal carbonate + acid → CO2 Example: Na2CO3 (aq) + 2 HCl (aq) → 2 NaCl(aq) + CO2(g) + H2O(l) 2. Metal sulfite + acid → SO2 K2SO3 (aq) + 2 HCl (aq) → 2 KCl(aq) + SO2(g) + H2O(l) 3. Metal + acid → H2 Remark: This is a single displacement reaction therefore the metal used in the reaction should be higher in the reactivity series than hydrogen. Zn (s) + 2 HCl (aq) → ZnCl2 (aq) + H2(g) 4. Metal sulfide + acid → H2S Na2S (aq) + 2 HCl (aq) → 2 NaCl (aq) + H2S (g) 5. Ammonium compound + base (alkaline solution) → NH3 NH4Cl (aq) + NaOH (aq) → NaCl (aq) + NH3 (g) + H2O (l) Exercise: Write the net ionic equations for each of the above 5 reactions. Answers 1. 2 H+ (aq) + CO3-2(aq) → CO2(g) + H2O (l) 2. 2 H+ (aq) + SO3-2(aq) → SO2(g) + H2O (l) 3. Zn(s) + 2 H+(aq) → Zn+2(aq) + H2(g) 4. 2H+ (aq) + S-2 (aq) → H2S (g)
Updated 65d ago
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You place a RBC (0.9%) into a 5% sugar solution. Which statement below is false? The RBC is hypotonic to the 5% solution Which is an example of a sensor in a negative homeostatic feedback loop? Chemoreceptor in carotid body For membrane fluidity experiment, the part of the experiment that actually validated that the membrane was fluid was: The labeled antibodies of the human and mouse intermixing An example of primary active transport would be a protein requiring ATP to transport sodium ions across the plasma membrane. True If a red blood cell is put in a solution and it hemolyzes, then the solution is considered to be: Hypotonic If your body temperature goes too high you can denature enzymes in your body. True What does an integrator do in a homeostatic pathway? Measures the signal coming in to a set point and send a signal out to the body Which of the following represents stages of the cell division (mitosis) in the proper sequence? Prophase, metaphase, anaphase, telophase Which is not true for proteins? They are comprised of mostly cellulose What would be a disturbance for blood glucose homeostasis (normal blood glucose set point = 77mg/dL)? A permanent decrease in insulin production from the Islets of Langerhans Dr. Bio measures your total cholesterol and he reports back to you that your level is 300 mg/ 100 ml of plasma. You do what? Eat more oatmeal and flax to increase your HDL level. How do you make an unsaturated fatty acid? Perform a dehydration synthesis reaction on a saturated fatty acid Which is false for antioxidants? They speed up reactions in your body Which molecules do not dissolve in water? Non-polar Which molecule requires a transport protein to get through the plasma membrane (either channel or carrier protein)? Two of the answers are correct Interphase is considered to be part of normal cell division (mitosis). False What is the function of ATP? All of the answers are correct What are the three kinds of lipids? Triglycerides, phospholipids, and steroids When glycerol combines with 3 fatty acids to form a triglyceride (fat), which of the following chemical reactions has occurred? Dehydration Synthesis How can you alter a protein’s shape? More than one answer is correct If a red blood cell is put into a solution and it maintains its shape, then the solution is considered to be: Isotonic Which molecule requires some type of transport protein to get through the plasma membrane? Sodium Ion Cofactors are molecules that activate enzymes. Which is not a cofactor? Mercury The nitrogenous bases found in DNA have complementary paring. Which pair is correct? C-G Which is not true for meiosis? Results in a gamete that is 2N In the diagram below the two solutions are separated by a semi permeable membrane. In which direction will net movement of water occur? From side A to side B Which is not a component of a DNA molecule: Ribose Sugar Phospholipids are similar to fatty acids except for? Phospholipids have a phosphate group Which is not true for cells? They allow diffusion of all molecules If you combine a molecule of glucose and fructose, which statement is true? You have formed sucrose Which is true for enzymes? Activity will increase until the enzyme becomes saturated What method would you use to get glucose into a cell along/down it’s concentration gradient (from high to low)? Facilitated Diffusion Which is not considered an integrator in a negative homeostatic feedback loop? Pancreas Which phase of the cell cycle is where cytokinesis takes place? Telophase What vitamin do we produce by sitting in the sun; it aids in calcium absorption from the small intestine? Vitamin D Why is it important to think about ion dissociation in the body? All the above In what order do you use macromolecules for fuel? Carbohydrates, lipids, proteins Which is false for cholesterol? It can dissolve in water/blood You place a RBC (0.9%) into a 0.5% sugar solution. Which statement below is false? The RBC is hypertonic to the 0.5% solution Which is not a membrane protein function? Protein synthesis Ingesting (eating) excess hydrophilic vitamins, such as vitamin C, results in excess vitamin C being stored in your tissues. False Diffusion is: The movement of molecules from an area of high molecular concentration to an area of low molecular concentration across a selectively-permeable membrane The hormone responsible for glucose uptake/removal from the blood is: Insulin What method would you use to get sodium ions into a cell against sodium’s concentration gradient (from low to high concentration)? Active Transport Which phase of the cell cycle is where the cell is functioning normally or doing its job? Interphase Evidence for mitochondria once being bacteria that our cells engulfed is: It has it’s own DNA Ionic molecules (ie NA+, K+) can diffuse straight through the plasma membrane. True What is the difference between cis and trans fatty acids? Cis fatty acids have hydrogens on the same side of the carbon double bond and trans fatty acids do not Cofactors are molecules that activate enzymes. Where do we get cofactors from? Vitamins found in fruits and vegetables RNA has what nitrogenous base in place of thymine? Uracil Large polar molecules (ie glucose) can diffuse straight through the plasma membrane? False Which lipoprotein is comprised of more protein and less cholesterol so it scavenges for cholesterol in the blood? High density lipoprotein A normal human being has 46 chromosomes (23 pairs/2N/diploid) in each somatic cell (body cell). True The three main compounds digested by the digestive system are? Fats, carbohydrates, and proteins Meiosis is the process in which our sex cells go from 46 chromosomes to 23 single chromosomes. True The effector in any negative feedback loop is usually: An organ/tissue If a red blood cell is put into a solution and it crenates (shrinks), then the solution is considered to be: Hypertonic Which statement is false for glycogen? It is a disaccharide Enzymes aid in digestion by? Lowering the energy required to break food apart Nonpolar molecules (ie CO2) can diffuse straight through the plasma membrane
Updated 81d ago
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Synthesis Reactions
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