CHEMISTRY COMMUNITY

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The order is supposed to be
solid | aqueous || aqueous | solid

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If the chemical reaction depends on the yield of product, or you are given a certain amount of reactants to work with.

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It depends on what units are given in the problem. Use whichever is simplest.

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Use q=mcdeltat when dealing with the slope part of the phase change diagram. Use the other equation when the line is flat (no phase change occurring).

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A positive delta G indicates that the reaction is nonspontaneous, or nonfavorable.

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When you plug in the temperature and other variables, as long as delta G is negative, then the reaction is spontaneous.

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The unit is kJ/mol

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The other variable in the ghost equation also factor in whether or not delta S is positive or negative.

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I thought of it as a spontaneous reaction because when the temperature is -10 degrees C, then snow precipitating is spontaneous, thus delta G is negative.

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skeleton equations don't involve e- or waters.

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OIL RIG
oxidation is loss (of e-)
reduction is gain (of e-)

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The nought symbol indicates standard conditions.

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yes, you will have to know how to do that.

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By using the gibbs free energy equation, you see the relationship between each component.

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Gibbs free energy will tell you if a reaction is spontaneous or not.

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Closed systems have a barrier that prevents matter from escaping. Open systems have no form of barrier that prevents anything from being transferred to the surrounding.

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You don't need to convert it when you're only using the difference in the temperatures in your equation because the differences will be the same. You need to convert when you're using a specific temperature (not the change) and when you are trying to find a ratio between initial and final temperatur...

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The naught symbol indicates that the conditions are standard.

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delta U is internal energy and q is the heat.

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Energy can be exchanged with the surroundings. Nothing can be exchanged in an isolated system.

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Yes, one of the points of adding the equations together is to cancel out compounds that are not needed.

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Yes, make sure that all states of matter can cancel out and then manipulate each equation (multiplying or flipping) so that you get the final equation. Add together the enthalpies to find the enthalpy of the reaction.

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You can calculate pH and pOH from [H30+] and [OH-] respectively by taking the negative log of the concentrations. This will indicate if the chemical compound is an acid or base.

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It is calculated by dividing the concentration of the conjugate acid by the concentration of the initial base and multiplying that by 100.

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It can be used for both!

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There is a list of common acids/bases that you could take a look at which could help you determine if a compound is an acid or base. You can also look at the pH if it is given, and that is a clear indicator of which one it is.

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Water can be a solid liquid or gas, but not aqueous.

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Q can be calculated at any given point of the reaction. K is calculated when the system is in equilibrium.

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You will be given this information from the question.

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Thank you for the churro review! I also really liked garlic bread(:

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The roman numerals correlate with the transition metal's oxidation number. Ag, Fe, Cu, and Pb are some examples of elements that need a roman numeral when naming them.

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OH2 and H2O are used depending on which element is doing the bonding. Two elements that bind together will be written right next to each other.

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OH2 has a charge of zero. Cl has a charge of 1-, so that means Fe has a charge of 2+ because the overall charge of the compound is 1+.

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Use the given constants until the end of the problem and then round to your significant figures!

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Yes, the molecular geometry and electron arrangements would be the same if there are no lone pairs.

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There are charts that are organised in a specific way that can help with memorizing. You can google molecular shapes and be able to find a chart!

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The periodic table that is provided is always the same, so you can refer to the past periodic tables that have been provided.

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Double bonds have a sigma and a pi bond!

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As electronegativity increases, the pull on the electrons is greater. This means that the electrons are closer to the nucleus, thus giving the molecule a smaller atomic radius.

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The stronger the bond, the higher the melting/boiling point.

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Bond lengths are the same. Resonance structures give different locations for the different types of bonds, but lengths of the bonds are the same.

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In nature, the bond lengths are going to be the same for double and triple and single bonds in a molecule.

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You would need to know the different bond lengths to gauge how long a bond length would be in relation to the given length. In other words, you need to be given at least one bond length in order to give a relative bond length in relation to the given.

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To let the structure be as stable as possible, a charge of 0 is the most stable. The outer elements can have a charge as long as the charges are symmetrical for it to still be stable.

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Elements that are past the 3rd period can have an expanded octet, but it depends on what the compound is to determine whether or not it needs to use an expanded octet.

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Longer bonds mean that they are weaker.

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Single bonds are longer than double bonds, and double bonds are longer than triple bonds. This is because of the strength of the bonds.

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Double bonds are shorter than single bonds because double bonds are stronger and more attracted to the protons in the nucleus. Single bonds are as strong, therefore they are not going to be as attracted to the nucleus.

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We don’t need to know how to use it to calculate anything.

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If delta x increases, then delta p will decrease.

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To add on, if the orbital you’re talking about isn’t the p orbital, how do you know the degeneracy?

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More protons means that the pull on electrons surrounding the atom is greater. This pull makes the atomic radius smaller.

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The symmetry helps us understand how the structures are shaped.

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Josephine Lu 1L wrote:Is the unit of work function Joules, or Joules per photon?

The unit for work is joules! And joules = kg.m^2.s^-2

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More often than not, the actual yield will be less than the theoretical yield because in reactions, there is always room to make error and chemical products and reactants could "escape" the experiment. The actual yield is the yield you get from conducting the experiment in real life, and t...

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It is completely possible! If the given molecular weight is calculated to be the same as the empirical formula's molecular weight, then it is the same!

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Diatomic elements only need to exist in pairs of atoms when they are standing alone. For instance, in OH-, you wouldn't need two hydrogen atoms because the hydrogen is not free standing. However, if you have hydrogen gas, you would need H2 because it is not attached to a different element.

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I always use three decimals for the molar mass from the given periodic table masses. At the very end of the problem is when I round any number that I use in my calculations. This ensures that I don't miss anything or have any miscalculations.

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If atoms are linked together, they form one compound. Count up each type of atom to form the compounds used in the equation and use them to make a balanced chemical equation.

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I usually use the most exact number (from the calculator) when dealing with the problem, and at the very end, I round to however many significant figures there are given from the problem.

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