Intro to Organic and Biochemistry Exam #1

C-Carbon atom.

Yes, H-O-O-H is a valid compound because it shows the hydrogens with 1 bond and the oxygens with 2 bonds.

The study of the structures and reactions of compounds and molecules.

Atomic mass of 12 -6 electrons in carbon = 6 neutrons.

O=O, because it has 2 bonds in oxygen.

Heptane.

4 carbon atom. Alkane formula: CnH2n+2.

Methane-Ethane.

Different compounds possessing the same molecular formula, but differing in connectivity.

It is the number of carbon atoms in a successive manner (one after another or the longest carbon chain). 3.

Combustion and halogenation.

When molecular halogens (F2, Cl2, Br2) react with alkanes and cycloalkanes, but only in the presence of heat or UV light. Ex. CH4+Cl2—–UV or Heat——CH3Cl+HCl

Methene is not a chemical compound. Methane, Ethane, and Ethene is a chemical compound.

Alkenes is more reactive than Alkanes.

Alkene are unsaturated hydrocarbons containing a double carbon bond, the general formula: CnH2n, where n is greater than 1. Nonpolar and insoluble in water.

Alkane are saturated hydrocarbons containing only single bonds. They undergo very few chemical reactions. The general formula: CnH2n+2.

Ethane( CH2=CH2+H2O——CH3CH3)

Propylene (aka propene).

Alkenes undergo addition reactions and aromatic compounds undergo substitution reactions with Br2.

Alkene or ether, depending on the temperature of the reaction.

Ethers.

Reaction of ethene with water.

There is 3 different forms of propanol: 1-propanol, 2-propanol, and 3-propanol.

Because there are stronger secondary forces between ethane molecules than between methanol molecules.

Silicon, Iodine, and Lead. Iodine is an element with the symbol I. Lead is an element with the symbol Pb. Silicon is an element with the symbol Si. Because water, quartz, and silicone are not listed in the periodic table, we know that they are not elements. Water, H2O, is a compound of the elements hydrogen and oxygen. Quartz, SiO2, is a compound of the elements silicon and oxygen. Silicone is a compound of silicon and various other elements.

Most of the atom’s mass but very little of its size. An atom is mostly empty space, with a small dense nucleus.

The element Se contains 34 protons per atom according to the periodic table. If the mass number is 78, the number of neutrons is 78-34=44 neutrons. A neutral atom has equal numbers of protons and electrons. An atom with a mass number of 65 and 36 neutrons has 65-36=29 protons. According to the periodic table, the element with 29 protons per atom is Cu. A neutral atom has equal numbers of protons and electrons. A neutral atom has equal numbers of protons and electrons. The element with 36 protons per atom is Kr. The mass number is the sum of the numbers of protons and neutrons: 36+49=85.

A bond is formed when elements share, gain, or lose electrons. Ionic bonds form when electrons are transferred from an atom of one element to an atom of another element. (One element gains electron from another element and one element transfer it to another element).Covalent bonds form when elements share electrons. (Two elements share electrons.)

The formula mass is the sum of each atomic mass in the formula, and the formula mass gives the mass of one molecule of the compound. Be sure to account for the number of atoms of each element in the formula by multiplying the atomic mass by the subscript numeral. Use the periodic table to determine the atomic mass of each element. a) C3H6 (3 x 12.011 amu)+(6 x 1.0079 amu)=42.080 amu b) C16H32O2 (16 x 12.011 amu)+(32 x 1.0079 amu)+(2 x 15.999 amu)=256.427 amu

Each neutral element has a certain number of valence electrons: carbon has 4, nitrogen has 5, and oxygen has 6 valence electrons. Of the given Lewis symbols, only the carbon and oxygen symbols are correct. The nitrogen atom should have 5 electrons.

There are 5 electrons around this symbol so it’s a 5A element with an electron configuration of ns2np3. (The element could be N, P, As, Sb, or Bi.) There are 6 electrons around this symbol so it’s a 6A element with an electron configuration of ns2np4. (The element could be O, S, Se, Te, or Po.)

For carbon to follow the octet rule and be neutral, it must make exactly four bonds. Therefore, we connect carbon to the four other atoms via single bonds. The bonds account for 8 of this molecule’s valence electrons. HCCl3 contains a C atom (with four valence electrons), one H atom (with one valence electron), and three Cl atoms (each with seven valence electrons), so the total number of valence electrons should be 4 1 3(7) = 26. Thus, we need 26 – 8 = 18 more electrons in the form of 9 lone pairs. Adding three lone pairs to each Cl atom completes their octets and accounts for the remaining 18 electrons.

For NCl3, the group number of N (group 5A) is lower than that of Cl (group 7A), making N the central atom. The bonding arrangements that will give each atom an octet are: 26 electrons and 24 electrons. NCl3 contains a N atom (with five valence electrons) and three Cl atoms (each with seven valence electrons) for a total 5 3(7)=26 valence electrons. So only the structure with 26 electrons is valid.

For carbon to follow the octet rule and be neutral, it must make exactly four bonds. Chlorine must make one bond and have three lone pairs. For hydrogen to follow the duet rule and be neutral, it must make exactly one bond.

CO2 should have 4 2(6)=16 valence electrons. The given structure shows 20 electrons (2 shared pairs and 8 unshared pairs). Thus, the structure is invalid even though each atom has an octet. Each F atom in OF2 is shown with 10 electrons (2 shared pairs and 3 unshared pairs), which is an octet-rule violation. Thus, the structure is invalid even though it has the correct total number of electrons. F2 should have 2(7)=14 electrons. The given structure shows 10 electrons (3 shared pairs and 2 unshared pairs). Thus, the structure is invalid even though each atom has an octet. The N atom in NO3- is shown with 6 electrons (3 shared pairs), which is an octet-rule violation. Thus, the structure is invalid even though it has the correct total number of electrons. Note that octet-rule violations don’t always indicate an invalid structure. For example, elements in the third period and beyond can have more than 8 electrons. Hydrogen, beryllium, and boron always have less than 8 (2, 4, and 6 electrons respectively). So really, C, N, O, and F are the only atoms that exclusively follow the octet rule, and that’s only true for molecules with an even number of electrons. For this reason, many instructors prefer to say the “octet suggestion” rather than the “octet rule”.

The arrangement of the atoms is given in the question. The carboxyl group has an -OH group bonded to the carbon atom of the C=O group.

Both atoms need an octet. Here are three possible bonding arrangments that give each atom 8 electrons. 14 electrons 12 electrons 10 electrons. The final step is to find the expected number of valence electrons for the formula. ClO- should have a total of 7+6+1=14 valence electrons. Thus, only the first structure is correct.

Water has a bent shape. The four electron groups on the central atom (two lone pairs and two bonded atoms) form an approximate tetrahedron such that the H-O-H bond angle is approximately 109.5. Repulsion between the lone pairs and the bonds reduces this bond angle somewhat (the actual bond angle is 104.5°).

Tetrahedral. For each carbon atom, the bonded atoms point towards the corners of a tetrahedron, located 109.5° apart. This is the shape that provides the maximum distance between the electron pairs that repel each other in 3-dimensional space.

In a solid, the particles vibrate in place, but they do not move relative to each other. In a liquid, the particles can move past one another, but there is not much space between the particles. In a gas, the particles have a great deal of space between them.

In a solid, the particles vibrate in place, but they do not move relative to each other. In a liquid, the particles can move past one another, but there is not much space between the particles. In a gas, the particles have a great deal of space between them.

Dipole-dipole attraction exists between polar molecules. Dispersion forces (a.k.a. London forces or van der Waals forces) are temporary dipoles that form between nonpolar molecules. Hydrogen bonding occurs when a hydrogen atom that is bonded to O, N, or F is attracted to the O, N, or F atom of another nearby molecule. Hydrogen bonding is stronger than dipole-dipole interactions because hydrogen bonding involves particularly polar bonds (those between H and N, O, or F) and also a lone pair to which the electron-deficient hydrogen atom is particularly attracted. The temporary dipole that characterizes dispersion forces is typically weaker than the permanent dipole of dipole-dipole interactions. However, in large molecules, there is room for more areas of temporary polarity, which can have a compounding effect, resulting in very strong intermolecular attraction. Paraffin wax is an example of a nonpolar substance with a particularly high melting point.

Small polar molecules are more soluble in water than larger or nonpolar molecules. •Ethane is nonpolar, and it is insoluble in water. •Although lauric acid contains a polar C=O group and a polar OH group, the nonpolar part of the molecule is large, and the molecule is insoluble in water. •Propene contains only nonpolar C-C, C=C, and C-H bonds. •1,4-Butanediol contains two polar OH groups, and the nonpolar part of the molecule is not very large. Therefore, 1,4-butanediol is the most water-soluble.

Soluble=KNO3, ZnBr2, and Pb(NO3)2. Insoluble=AgBr, CaSO4, and FeCO3.

In compounds, oxygen tends to have a -2 oxidation state and hydrogen tends to have a 1 oxidation state. The overall chrage on COH2 is zero, so if x is the oxidation state of C, then x (-2) 2( 1) = 0, and x = 0. As an anion, Br has a -1 charge. Monoatomic ions have oxidation states equal to their ionic charges. The overall chrage on FeBr2 is zero, so if x is the oxidation state of Fe, then x 2(-1) = 0, and x = 2.

Oxidation half-reaction: 2Ag0—–2Ag+2e- Reduction half-reaction: Cl2+2e- ——-2Cl-
First, identify which element is being oxidized and which is being reduced. Oxidiation is the loss of electrons, which corresponds to an increase in oxidation state. Reduction is the gain of electrons, which corresponds to a decrease in oxidation state. Note that both elements start out as neutral, uncombined elements, with oxidation states of zero. In the product, silver is a cation, which means its oxidation state has increased from what it was in the reactants. Chlorine is an anion in the product, which means its oxidation state has decreased from what it was in the reactants. Thus, silver is oxidized and chlorine is reduced. In the compound AgCl, the ions are Ag and Cl-. Thus, the oxidation half-reaction should contain Ag as the reactant and Ag as the product. It should also contain one electron on the more positive side to balance the charge. The reduction half-reaction should contain Cl2 as the reactant and Cl- as the product. A coefficient of 2 is needed in front of the product to balance the number of chlorine atoms. Finally, two electrons are needed on the more positive side to balance the charge.

The energy of a collision between atoms or molecules must be greater than the activation energy (Ea) for bonds to be broken. Decreasing the temperature decreases the kinetic energy of the reactants, and the reaction goes more slowly. Increasing the concentration of reactants increases the number of collisions, and the reaction goes faster. Two or more atoms must collide, with proper orientation, with energy greater than or equal to the activation energy for a reaction to occur.The activation energy, Ea, of a reaction is the energy required for the reaction to occur (for bonds to be broken). For the reaction to take place, two or more atoms or molecules must collide with proper orientation and sufficient force – greater than or equal to Ea. The greater the Ea, the slower the reaction; the lower the Ea, the faster the reaction. Increasing the temperature increases the kinetic energy of the reactants. The reactants move faster, colliding more frequently and with more energy. Therefore, increasing the temperature increases the rate of the reaction (the reaction goes faster). Increasing the concentration of reactant increases the probability that reactants will collide. Therefore, increasing the amount of reactant increases the reaction rate. In an exothermic reaction, the energy of the products is lower than that of the reactants, and ΔH is negative. In an endothermic reaction, the energy of the products is higher than that of the reactants, and ΔH is positive.

Increased rate of the forward reaction and the rate of the reverse reaction. Decreased activation energy of the forward reaction and the activation energy of the reverse reaction. the mechanism. Note that the identities of the reactants and products are the same for both the catalyzed and uncatalyzed reactions. In other words, the catalyst has no effect on the overall reaction. Since enthalpy is the difference between the products and the reactants, we can see that enthalpy is also unaffected by a catalyst. Think of activation energy is a hindrance to reaction progress. A higher activation energy results in a slower reaction. A catalyst increases the rate of both the forward and reverse reactions by providing an alternate path of lower activation energy in either direction. Notice that the difference between the energy of the reactants and the transition state is lower for the catalyzed (purple) reaction than it is for the uncatalyzed (red) reaction, illustrating that a catalyst decreases the activation energy of the forward reaction. Also notice that the difference between the energy of the products and the transition state is lower for the catalyzed (purple) reactant than it is for the uncatalyzed (red) reaction, illustrating that a catalyst decreases the activation energy of the reverse reaction. A catalyst is able to lower the activation energy of a reaction because it provides an alternate path or mechanism with lower-energy transition states. In the diagram, this is depicted by the two humps in the catalyzed reaction, representing two steps and two transitions states, as opposed to one hump (one step and one transition state) in the uncatalyzed reaction.

A substrate must bind to the active site before catalysis can occur. Generally, an enzyme is specific for a particular substrate. For example, thrombin catalyzes the hydrolysis of the peptide bond between Arg and Gly. Catalysis occurs at the active site, which usually consists of a crevice on the surface of the enzyme. An enzyme yields a specific product, whereas a nonbiological catalyst may produce more than one product, and side reactions may occur. A catalyst increases the rate of a reaction. Enzymes are biological catalysts. Platinum is an example of a nonbiological catalyst. In an enzyme catalyzed reaction, the reactant is called the substrate. The substrate binds to the active site, which is generally in a crevice on the surface of the enzyme where amino acid functional groups are positioned to facilitate breaking and forming bonds. Enzymes are generally highly reaction and/or structure specific. Nonbiological catalysts typically facilitate many types of reactions, and are therefore called nonspecific catalysts.

The concentrations of reactants and products remain constant, reactants are still being converted to products (and vice versa), and the rates of the forward and reverse reactions are equal. Equilibrium occurs when the rates of the forward and reverse reactions are equal. Thus, even though both reactions are occuring (reactants are being converted to products and vice versa), there is no change in concentration. In other words, each species is being produced and consumed at the same rate.

K = 3000 and K = 6× 108. The equilibrium constant, K, expresses the relationship between the concentrations of the species at equilibrium. In this case, K= B/A When [B] is greater than [A], K is greater than 1. Of the given values, 6× 108 and 3000 are greater than 1, but 0.2 and 5× 10-7 are less than 1.

The Keq expression for this reaction is Keq=[H2]3[N2]/[NH3]2. Now substitute the appropriate values into the Keq expression. Keq=(0.400)3(0.800)/(0.250)2=0.819

[H ] is the antilog of the negative pH. [H+]=10-pH=10-4.82=1.51 x 10-5 M.

The pH of a solution is the negative logarithm of the hydronium ion concentration. pH=-log[H3O+] so [H3O+]=10-pH=10-4.10=.000079. You can determine the hydroxide ion concentration two ways: [OH-]=Kw/[H3O+]=1.0 x 10-14/.000079=1.3 x 10-10 M.

Organic=C6H12O6, C4HgNO2, CH3CH2CH2—–SH. Inorganic=KCl, CoSO4, H2O, Cl6—-B—-Cl6—–Cl6. Organic compounds include hydrocarbons and their derivatives. Therefore, organic compounds contain the element carbon. However, not all compounds that contain carbon are organic (for example, carbonates). The compounds C6H12O6, C4H9NO2, and 1-propanethiol are organic. Inorganic compounds are compounds that are not organic. The compounds KCl, CoSO4, H2O, and boron trichloride are not organic.

a) Each bond in this compound is a single bond. b) Each carbon-hydrogen bond is a single bond. One of the carbon-carbon bonds is a double bond (C=C).

a) The only possible arrangement is for the two carbon atoms to be bonded to each other (hydrogen can only form one bond, so there cannot be a hydrogen atom between the two carbon atoms). Each carbon atom is bonded to three hydrogen atoms. b) The ony possible arrangement is for the oxygen atom to be bonded to the carbon atom. The carbon atom is bonded to three hydrogen atoms, for a total of four bonds and a full octet. The oxygen atom forms two bonds: one bond with carbon and one bond with hydrogen. This accounts for four electrons. To complete the octet, add two lone pairs of electrons to oxygen.

a) This is the line-angle formula that represents 3-methyl-2-heptene. The double bond between carbons 2 and 3 indicates that this is an alkene, hence the naming: 3-methyl-2-heptene. b) This structure represents ethylbenzene. Benzene is an aromatic compound. c) The condensed structural formula can be drawn out to its complete structural formula (displayed below): The name of this structure is 2-pentyne. There is a triple bond between carbons 2 and 3, resulting in an alkyne hydrocarbon. d) Once again the condensed structural formula can be drawn out to its complete structural formula (displayed below): This compound is butane. The structure contains no double or triple bonds, therefore, it is considered unsaturated or an alkane.

Ethane is an alkane with the molecular formula C2H6. Propane has the molecular formula C3H8. A complete structure shows all the hydrogen atoms.

The number of hydrogen atoms in an alkane is represented by the mathematical formula CnH2n 2, where n is the number of carbon atoms. Therefore, there are 2(5) 2 = 12 hydrogen atoms in an alkane with carbon atoms. An alkane with 11 carbon atoms contains 2(11) 2 = 24 hydrogen atoms.

Tetrahedral. For each carbon atom, the bonded atoms point towards the corners of a tetrahedron, located 109.5° apart. This is the shape that provides the maximum distance between the electron pairs that repel each other in 3-dimensional space.