Search found 65 matches
- Sun Mar 17, 2019 11:14 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Le Chatlier Principle
- Replies: 10
- Views: 2118
Re: Le Chatlier Principle
adding a catalyst has no effect on the equilibrium, it just speeds up reaction.
- Sat Mar 16, 2019 1:45 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: applying Le Chatelier's Principle
- Replies: 4
- Views: 793
Re: applying Le Chatelier's Principle
You determine the reaction is not at equilibrium and that Q<K, therefore there is too much reactant, meaning to reach equilibrium the reaction will need to produce more product, thus going in the forward reaction.
- Sat Mar 16, 2019 1:40 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Final [ENDORSED]
- Replies: 9
- Views: 1140
Re: Final [ENDORSED]
They should give us the Ecell values needed like in test 2.
- Sat Mar 16, 2019 1:37 pm
- Forum: Balancing Redox Reactions
- Topic: How to tell if its in acidic or basic
- Replies: 6
- Views: 687
Re: How to tell if its in acidic or basic
They should tell you if it's acidic or basic.
- Sat Mar 16, 2019 1:23 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Standard Conditions
- Replies: 2
- Views: 640
Re: Standard Conditions
n is the moles of electrons, and to find n you should do the half reactions and determine how many electrons were exchanged in the half reactions.
- Thu Mar 07, 2019 12:19 am
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: E cell
- Replies: 5
- Views: 492
Re: E cell
E^o is the standard reduction potential, which means under standard conditions: 1atm, 1M, and at 25 degrees Celsius
E is the cell potential, which changes.
E is the cell potential, which changes.
- Thu Mar 07, 2019 12:15 am
- Forum: General Rate Laws
- Topic: Reaction Order
- Replies: 4
- Views: 518
Re: Reaction Order
For a zero order rate the units are mol/L*s
For a 1st order rate the units are 1/s
For a 2nd order rate the units are L/mol*s
For a 1st order rate the units are 1/s
For a 2nd order rate the units are L/mol*s
- Thu Mar 07, 2019 12:05 am
- Forum: Second Order Reactions
- Topic: graph for second order
- Replies: 7
- Views: 792
Re: graph for second order
The graph for a 2nd order reaction is a linear graph with a positive slope.
- Thu Mar 07, 2019 12:04 am
- Forum: Van't Hoff Equation
- Topic: Temp Units
- Replies: 11
- Views: 1353
Re: Temp Units
For the Van Hoff equation you use units of K for temp, and if given in C, convert by adding 273.
- Thu Mar 07, 2019 12:02 am
- Forum: First Order Reactions
- Topic: 1/2 life
- Replies: 7
- Views: 802
Re: 1/2 life
The 1/2 life for a first order does not depend on the initial concentration.
- Wed Mar 06, 2019 11:58 pm
- Forum: General Rate Laws
- Topic: Which law?
- Replies: 2
- Views: 300
Re: Which law?
Sometimes the question tells you which order it is, and from there you can determine the rate. Otherwise, there should be sufficient data given to dtermine which rate to use.
- Wed Feb 20, 2019 10:51 pm
- Forum: Ideal Gases
- Topic: units
- Replies: 15
- Views: 1391
Re: units
K doesn't have any units, due to it being a ratio (in which the units cancel)
- Wed Feb 20, 2019 10:44 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: When does delta U equal zero?
- Replies: 17
- Views: 8319
Re: When does delta U equal zero?
delta U is equal to zero when the reaction is isothermal, meaning temperature is constant.
- Wed Feb 20, 2019 10:42 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Delta G a state function?
- Replies: 23
- Views: 2839
Re: Delta G a state function?
Gibbs Free Energy is a state function, all the properties of the equation deltaG = deltaH - T(deltaS) are also state functions.
- Wed Feb 20, 2019 10:38 pm
- Forum: General Science Questions
- Topic: Midterm
- Replies: 5
- Views: 863
Re: Midterm
Ka2 is the second deprotonation of phosphoric acid
- Mon Feb 11, 2019 2:12 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Conversions
- Replies: 4
- Views: 472
Re: Conversions
Most, if not all the equations and conversions we will need are on the constants and formulas page. Of course we do need to know how to rearrange the equations for certain problems.
https://lavelle.chem.ucla.edu/wp-conten ... ations.pdf
https://lavelle.chem.ucla.edu/wp-conten ... ations.pdf
- Mon Feb 11, 2019 2:06 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Bond enthalpies
- Replies: 10
- Views: 920
Re: Bond enthalpies
knowing the Lewis structure is helpful but the bond dissociation energies will be given which will also help you figure out how the bonds are formed or broken.
- Mon Feb 11, 2019 2:01 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Hess's Law
- Replies: 5
- Views: 533
Re: Hess's Law
The test should provide the chemical equations, but knowing the format of a combustion and how acids go from HA--> A- + H+
- Mon Feb 04, 2019 1:38 pm
- Forum: Phase Changes & Related Calculations
- Topic: Heat and Condensation
- Replies: 9
- Views: 959
Re: Heat and Condensation
Condensation releases energy.
- Mon Feb 04, 2019 1:34 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Closed and Isolated
- Replies: 10
- Views: 747
Re: Closed and Isolated
In a closed system matter can't exchange with the surroundings but energy can in forms of heat or work, a closed system can also have a fixed volume.
In an isolated system nothing exchanges with the surroundings .
In an isolated system nothing exchanges with the surroundings .
- Mon Feb 04, 2019 1:32 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Examples of Open Closed Isolated
- Replies: 5
- Views: 2072
Re: Examples of Open Closed Isolated
In an open system matter and energy can exchange with the surroundings, an example is a beaker of water. In a closed system energy can exchange with the system, an example is a sealed beaker of water. In a isolated system nothing exchanges with the surroundings, an example is a combustion of glucose...
- Mon Jan 28, 2019 1:04 am
- Forum: Ideal Gases
- Topic: pH and pOH
- Replies: 18
- Views: 1961
Re: pH and pOH
The question will ask you to solve for pH or pOH, and the problem will also give you sufficient information to be able to solve for this.
- Thu Jan 24, 2019 4:21 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Tricks for identifying Strong/Weak Acids & Bases
- Replies: 6
- Views: 587
Re: Tricks for identifying Strong/Weak Acids & Bases
Does anyone know of any tips or tricks that will allow you immediately to identify an acid or base as weak or strong? For strong bases and strong acids, it would help to memorize the list of strong acids and bases, because then you know anything that is not a strong base or acid, has to be weak. Al...
- Wed Jan 23, 2019 9:39 pm
- Forum: Phase Changes & Related Calculations
- Topic: ∆Hsub=∆Hfus+∆Hvap
- Replies: 3
- Views: 556
Re: ∆Hsub=∆Hfus+∆Hvap
How does ∆Hsub=∆Hfus+∆Hvap work? Thanks! Because Enthalpy is a state function, its properties can be added or subtracted. We know that ∆Hvap= Hvapor-Hliguid and that ∆Hfus=Hliquid-Hsolid. For sublimation we are going from a solid to a liquid and a liquid to a vapor, which is two steps, therefore we...
- Fri Jan 18, 2019 7:22 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Pressure
- Replies: 3
- Views: 454
Pressure
How does a change in pressure affect the equilibrium in a reaction?
- Fri Jan 18, 2019 7:18 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Buffers - weak acid
- Replies: 4
- Views: 3222
Re: Buffers - weak acid
Buffers can consist of a weak acid and its conjugate base, as well as the salt. Or vice-versa, a weak base and its conjugate base with the salt.
- Fri Jan 18, 2019 7:16 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Understanding Q
- Replies: 9
- Views: 769
Re: Understanding Q
Q alone tells you nothing, but once compared to K, it tells you where the reaction is in terms of reaching the equilibrium concentration.
- Tue Jan 15, 2019 9:26 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Hydrofluoric Acid
- Replies: 3
- Views: 380
Re: Hydrofluoric Acid
HF, hydrofluoric acid is a weak acid.
- Tue Jan 15, 2019 8:59 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Equilibrium in relation to K and Q
- Replies: 5
- Views: 412
Re: Equilibrium in relation to K and Q
Calculating the values of K and Q requires the same process of solving. The only difference is that K tells you the equilibrium of the reaction, whereas Q tells you where you are on the path to equilibrium. This is why Q is useful when comparing it to K.
- Tue Jan 15, 2019 8:54 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Aqueous solution
- Replies: 2
- Views: 182
Aqueous solution
I know solids and liquids aren't included when calculating the equilibrium constant. Are aqueous solution included when calculating the equilibrium constant?
- Sat Dec 08, 2018 5:44 pm
- Forum: *Making Buffers & Calculating Buffer pH (Henderson-Hasselbalch Equation)
- Topic: Final Exam
- Replies: 8
- Views: 2412
Re: Final Exam
Just to be clear we only need to conceptually understand Ka and Kp values and equilibrium constants but we do not actually have to solve for this or use these factors for anything except determining which acid or base is stronger? Yes that's right, we only need to conceptually understand Ka and Kp....
- Sat Dec 08, 2018 5:43 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Determining the Coordination number
- Replies: 3
- Views: 199
Re: Determining the Coordination number
Anna O 1A wrote:Is the coordination number determined by the number of atoms attached to a central atom, the number of bonds (including double and triple) or the number of regions of electron density?
The coordination number is determined by the number of bonds.
- Sat Dec 08, 2018 5:41 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Acid Strength
- Replies: 2
- Views: 576
Re: Acid Strength
Isabel Nakoud 4D wrote:Why is Structure 2 a stronger acid than Structure 4?
Because the electron withdrawing ability of H is greater than CH3 and as there is more electron withdrawing ability, the acidity increases.
- Sat Dec 08, 2018 5:35 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSEPR
- Replies: 4
- Views: 554
Re: VSEPR
jane_ni_3b wrote:For something with the formula AXE3, would the bond angles be 180 because the molecular shape is linear?
Yes the bond angles would be 180 because its shape is linear.
- Sat Dec 08, 2018 5:33 pm
- Forum: Bronsted Acids & Bases
- Topic: How to tell the difference between Lewis + Bronsted
- Replies: 1
- Views: 408
Re: How to tell the difference between Lewis + Bronsted
I understand the electron/proton acceptor/donor concept, but how can you tell if a molecule is a Lewis acid/base or Bronsted acid/base? Examples would be much appreciated A molecule can be more than one type of acid or base, it just depends on which definition you apply. For most of the problems we...
- Sat Dec 08, 2018 5:26 pm
- Forum: Coordinate Covalent Bonds
- Topic: polydentates
- Replies: 5
- Views: 633
Re: polydentates
There's no easy way to know whether a coordination compound is polydentate, for this it is helpful to draw the lewis structure. But it is also good to know that bidentate ligands are ethylenediamine (en), and the oxalate ion (ox). Ethylenediaminetetraaceticacid acid (EDTA) is a hexadentate ligand an...
- Sat Dec 08, 2018 5:21 pm
- Forum: Bronsted Acids & Bases
- Topic: Oxoacids
- Replies: 1
- Views: 323
Re: Oxoacids
For oxoacids, the more electronegative the central atom, the more acidic the molecule will become. For a binary acid, strong acids like HCl are always strong, but the weaker the bond between the nonmetallic and hydrogen bond, the esier it is for H2O to remove the H+
- Sat Dec 08, 2018 5:14 pm
- Forum: Lewis Structures
- Topic: Lewis Acids & Bases
- Replies: 3
- Views: 611
Re: Lewis Acids & Bases
To tell if an element is a lewis acid or base just remember that a lewis acid is a species that accepts an electron pair like BF3 and a lewis base is a species that donates an electron pair like NH3.
- Sat Dec 08, 2018 5:10 pm
- Forum: SI Units, Unit Conversions
- Topic: Final Time
- Replies: 1
- Views: 460
Re: Final Time
The time given to us is 3 hours, and its just up to one to distribute the time between each question evenly or however one would like.
- Sat Dec 08, 2018 4:55 pm
- Forum: Lewis Acids & Bases
- Topic: salts in acids and bases
- Replies: 2
- Views: 174
Re: salts in acids and bases
905085650 wrote:Can someone explain to me the effect that salts have on acids and bases respectively?
Thank you!!
A salt containing an acid will lower the solutions pH whereas a salt containing a base will raise the solutions pH.
- Sat Dec 08, 2018 4:41 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Concept of Chelation
- Replies: 3
- Views: 399
Re: Concept of Chelation
A chelate is a coordination compound containing a ligand bonded to a central at two or more points, usucally froming a ring. so if a coordination compound contains at least one non-monodentate ligand it's considered a chelate. An exapmle is ironn in hemoglobin.
- Sat Dec 08, 2018 4:35 pm
- Forum: Amphoteric Compounds
- Topic: Amphoteric vs. Amphiprotic
- Replies: 1
- Views: 283
Re: Amphoteric vs. Amphiprotic
905085650 wrote:Can someone explain the difference between amphoteric and amphiprotic and give me an example of each?
Thank you!!
Amphoteric is a compound that can act as a base and an acid, like H2O
Amphiprotic is a substance that can donate and accept protons or H+, like amino acids
- Sat Dec 08, 2018 4:12 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Acids and Bases
- Replies: 5
- Views: 862
Re: Acids and Bases
404905747 wrote:Is there any easy way to identify a strong acid or strong base besides just memorizing them?
No, just memorize them, and if you have memorized them, then anything that is not a strong acid, is a weak acid.
- Sat Dec 08, 2018 4:11 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Acids and Bases
- Replies: 5
- Views: 862
Re: Acids and Bases
Some basics are that there is a Lewis and a Bronsted definition to acids and bases. A lewis acid a species that accepts an electron pair(ex. BF3) and a lewis base is a species that donates and electron pair (ex. NH3). Whereas, a bronsted acid is a proton donor and donates a hydrogen ion (ex. HCl) an...
- Sat Dec 08, 2018 3:56 pm
- Forum: Amphoteric Compounds
- Topic: polydentate
- Replies: 4
- Views: 660
Re: polydentate
What are polydentates and monodentates? Is there a certain list we should memorize? monodentate is a ligand that binds at 1 site and a polydentate is when a ligand binds to more than 1 site. I don't know of there is a list to memorize, but it would be helpful to know that some bidentate ligands are...
- Sat Dec 08, 2018 3:49 pm
- Forum: Conjugate Acids & Bases
- Topic: Strong acids and bases to memorize
- Replies: 9
- Views: 1548
Re: Strong acids and bases to memorize
Why would strong acids be conjugates of weak bases and vis versa? This concept escapes me. A conjugate base is the molecule that is formed after an acid loses a proton. An acid or base and its conjugate are inversely proportional in terms of strength. Therefore the stronger the acid the weaker its ...
- Sat Dec 08, 2018 3:37 pm
- Forum: Conjugate Acids & Bases
- Topic: Strong acids and bases to memorize
- Replies: 9
- Views: 1548
Re: Strong acids and bases to memorize
Strong Acids: HCl, HBr, HI, HNO3, HClO3, HClO4, and H2SO4
Stong Bses: LiOh, NaOH, KOH, RbOH, CsOH, Ca(OH)2, Ba(OH02, and Sr(OH)2
Stong Bses: LiOh, NaOH, KOH, RbOH, CsOH, Ca(OH)2, Ba(OH02, and Sr(OH)2
- Sat Dec 08, 2018 3:32 pm
- Forum: Naming
- Topic: en and edta
- Replies: 3
- Views: 651
Re: en and edta
Bijan Mehdizadeh 1E wrote:Could someone please explain to me what en and edta are?
en and edta are ligands.
en is a neutral ligand named ethylenediamine
edta is an anionic ligand named ethylenediaminetetraacetato
- Sat Dec 08, 2018 3:12 pm
- Forum: Naming
- Topic: Do we have to memorize some of the ligand names?
- Replies: 3
- Views: 324
Re: Do we have to memorize some of the ligand names?
Will we be asked to name a compound in final? If so, do we have to memorize some of the ligand names? Yes you do have to memorize the ligand names. Lavelle has a link that leads to the name of the ligands on the class website. https://lavelle.chem.ucla.edu/wp-content/supporting-files/Chem14A/Naming...
- Sat Dec 08, 2018 3:10 pm
- Forum: Lewis Acids & Bases
- Topic: H vs H30+
- Replies: 2
- Views: 359
Re: H vs H30+
Soyoung Park 1H wrote:How are hydrogen atoms and hydronium ions the same?
H+ and H3O+ are the same in that the hydronium ion is just the H+ attached to a water molecule.
- Sat Nov 10, 2018 6:07 pm
- Forum: Resonance Structures
- Topic: Bond Lengths
- Replies: 6
- Views: 921
Re: Bond Lengths
[quote="Daniela Alvarado 3B"]Does the bond length change depending on where the double bond is in the resonance structures?[/quot The bond lengths are the average all the bonds in the resonance structures , so where the double bond is in the resonance structure is already taken into consid...
- Sat Nov 10, 2018 5:44 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Shapes
- Replies: 5
- Views: 1544
Re: Shapes
Are all molecules with four bonding pairs tetrahedral? What makes the difference if they are not? All molecules with four bonding pairs and no lone pairs are tetrahedral. But if there was a lone pair, then it would be a trigonal pyramid, and so on. If a molecule has more or less than four bonding p...
- Sat Nov 10, 2018 5:37 pm
- Forum: Ionic & Covalent Bonds
- Topic: Dissociation Energy
- Replies: 3
- Views: 384
Re: Dissociation Energy
Why is the dissociation energy of a covalent bond, like N2, 932 kJ/mol and an ionic bond's, like NaCl, is -250 kJ/mol? (I wrote these down on my notes from the lecture). Since ionic bonds are stronger, wouldn't it have a much higher dissociation energy than N2? Why is it's dissociation energy negat...
- Sun Nov 04, 2018 3:47 pm
- Forum: Octet Exceptions
- Topic: Lewis acids and bases
- Replies: 3
- Views: 421
Re: Lewis acids and bases
What are some other examples of Lewis acids and bases other than the examples from lecture? A lewis base is a molecule that will donate a pair of electrons to another atom. Some examples are NH3 and F-. A lewis acid is a molecule that will accept a pair of electrons. Some examples are AlCl3 and BH3.
- Sun Nov 04, 2018 3:41 pm
- Forum: Lewis Structures
- Topic: Exceptions to the Octet Rule
- Replies: 4
- Views: 301
Re: Exceptions to the Octet Rule
claireg wrote:What are some examples of elements in compounds that exemplify exceptions to the octet rule and the reasons behind them?
Exceptions to the octet rule are atoms like, phosphorus, Sulfur, and Chlorine, this is because these elements have the d-orbital.
- Sun Nov 04, 2018 3:38 pm
- Forum: Photoelectric Effect
- Topic: intensity
- Replies: 4
- Views: 373
Re: intensity
how does increasing the intensity of the incoming photon affect the energy of the photon. Does it increase its energy, and if so, does that increase the number of electrons that will be emitted? Increasing the intensity increases the number of photons, because intensity and the number of photons ar...
- Sun Oct 28, 2018 4:44 pm
- Forum: Trends in The Periodic Table
- Topic: Exceptions to electron configuration
- Replies: 3
- Views: 485
Re: Exceptions to electron configuration
How are the exceptions to electron configuration determined? It explains in the textbook why they set up the configuration in certain elements this way but what differentiates copper and another metal? The exceptions to electron configuration are the groups of 6( chromium) and 11(copper). These two...
- Sun Oct 28, 2018 4:31 pm
- Forum: Lewis Structures
- Topic: octets
- Replies: 13
- Views: 1117
Re: octets
How can you distinguish if an element has a full octet? Does each orbital have to have a full octet before moving to the next orbital? Only noble gasses in their natural state have an octet. However, there are two ways to figure out how many electrons an element needs to complete an octet. One, you...
- Sun Oct 28, 2018 4:22 pm
- Forum: Ionic & Covalent Bonds
- Topic: Trend of Ionic Radii
- Replies: 5
- Views: 514
Re: Trend of Ionic Radii
The radius increases you go down a group(column) and the radius decreases as you go from left to right of a period.
- Fri Oct 12, 2018 9:13 am
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Balmer and Lyman series
- Replies: 4
- Views: 325
Re: Balmer and Lyman series
Why are these important? What are they? The Balmer and Lyman series are important because they help determine the energy level of electrons, and this is important when using Rydberg's equation. The Balmer series is used when in the visible spectrum, with n1=2. The Lyman series is used in the UV spe...
- Thu Oct 11, 2018 11:14 pm
- Forum: *Black Body Radiation
- Topic: The Importance of Black Body Radiation (?)
- Replies: 5
- Views: 844
Re: The Importance of Black Body Radiation (?)
In Monday's notes we wrote that the description if light as photons explains the intensity profile of black body radiation but have yet to talk about it again. Are we supposed to know the concept/definition of black body radiation? Is there any importance or significance to black body radiation? Gr...
- Thu Oct 11, 2018 11:05 pm
- Forum: Properties of Light
- Topic: How light behaves
- Replies: 8
- Views: 580
Re: How light behaves
I cannot conceptualize light being both photon (PACKETS) of energy and wavelengths. I find it difficult to exercise this into equations when I do not understand how it can be both and have one number. Please explain and possibly use equations in your explanation if possible. If not that is okay, an...
- Fri Oct 05, 2018 12:53 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: answer accuracy
- Replies: 4
- Views: 407
Re: answer accuracy
When I solve problems I don’t round until the very end and keep all my sigfigs but sometimes the answer I get is 0.01-0.02 digits different from the one in the solution manual. Will this be a big problem on the homework/test? I would ask your TA, because they will be grading our homework and test, ...
- Fri Oct 05, 2018 12:34 pm
- Forum: Properties of Light
- Topic: Energy Function
- Replies: 1
- Views: 147
Re: Energy Function
In the equation E= -hR/n^2 h, represent Plank's constant which is 6.626x10^-34J/s R, is Rydberg's constant which is 3.29x10^15 Hz n, is the number of the energy level of an electron (this is the quantized value) Overall, this contributes to finding the amount of energy contained in one electron whil...
- Fri Oct 05, 2018 12:17 pm
- Forum: SI Units, Unit Conversions
- Topic: SI Units on tests
- Replies: 5
- Views: 564
Re: SI Units on tests
I would expect that he would want us to write our final answers in SI units unless otherwise stated, like if the final answer is looking for an answer in g as opposed to kg. I do know that our TA's are grading our exams, therefore it might vary per TA too.