# Search results

1. ### Buffer Capacity

What is the smallest amount of solid NaOH that will exceed the buffer capacity 500mL of a buffer that is 0.4M in acetic acid and 0.15M in NaOAc? a)5.69 b)5.16 c) 4.74 d) 4.31 e)3.00 grams Since this is a strong base, we only need to deal with the 0.4M of acetic acid. so 0.4M *.5L =...
2. ### Partial Pressure Equilibrium lab

Pure solid ammonium carbamate, NH4CO2NH2, is allowed to dissociate into a vacuum according to the equation: NH4CO2NH2(s) ---> 2 NH3(g) + CO2(g) At 25oC, the total pressure of the gases in equilibrium with the solid is 0.116 atm. If carbon dioxide, CO2, was then added, sufficient to have...
3. ### Oscillation of object on spring - Find speed

A massless spring hangs from the ceiling with a small object attached to its lower end. the object is initially held at rest in a position y such that the spring is at its rest length(not stretched). The object is then released from y and oscillates up and down, with its lowest position being 10...
4. ### Limit problem

How do you find the limit to: Lim x->0+ sqrtx/(1-cosx) I use the L'Hopital rule and i get lim x->0+ 1/(2sqrtx*sinx) and I can't get anywhere after this. I even tried multiplying by sqrtx/sqrtx to get rid of the sqrtx at the beginning, but it still doesn't work. Please help, thanks.
5. ### Joined Spring problem

Two springs with a spring constant of k = 6430 N/m are joined and connected to a block of mass 0.245 kg. The system is then set oscillating over a frictionless surface. What is the frequency of the oscillations? This is what I think is the correct approach to this question: since the...
6. ### Limit problem

How do you find the limit to: Lim x->0+ sqrtx/(1-cosx) I use the L'Hopital rule and i get lim x->0+ 1/(2sqrtx*sinx) and I can't get anywhere after this. I even tried multiplying by sqrtx/sqrtx to get rid of the sqrtx at the beginning, but it still doesn't work. Please...
7. ### Oscillating spring problem

A massless spring hangs from the ceiling with a small object attached to its lower end. the object is initially held at rest in a position y such that the spring is at its rest length(not stretched). The object is then released from y and oscillates up and down, with its lowest position being 10...
8. ### Joined Springs

Two springs with a spring constant of k = 6430 N/m are joined and connected to a block of mass 0.245 kg. The system is then set oscillating over a frictionless surface. What is the frequency of the oscillations? This is what I think is the correct approach to this question: since the...
9. ### Hexyl ethanoate or octanoic acid?

Which is more soluble in hexane, hexyl ethanoate or octanoic acid? I'm thinking it's octanoic acid with the longer uninterrupted hydrocarbon chain, where as the ester's longest uninterrupted hydrocarbon chain is composed of six carbons. Is this correct? If not can you please explain why? Thanks.
10. ### Cyclohexene and toluene + sulfuric acid

For cyclohexene and sulfuric acid reaction, is a precipitate suppose to form? the results looked yellow-orange ish, but it became murky. I'm suppose to note the solubility change, but i don't know what to say for it. Please help thanks. For Toluene though, i heated it as well, and there was...
11. ### Toluene + bromine

I mixed toulene + bromine and dichloromethane together, to see if a reaction occurs(decolourizes). However, i read in my lab manual that this test should be negative for aromatics. So is toluene suppose to be negative as well? If so i think something went wrong with my experiment. Thanks.
12. ### Proving inflection points

I know this is a chem question in general, but the steps needed to solve this are more mathematical. This is not a homework question, but my prof came up with the concept of determining the inflection point on a titration graph with 2 pKas. He simply told us that it was the average of the 2...
13. ### Proving inflection points - Titration

This is not a homework question, but my prof came up with the concept of determining the inflection point on a titration graph with 2 pKas. He simply told us that it was the average of the 2 pKa values. However, he also just mentioned that it can also be proven through calculations, but he never...
14. ### Calculating pKa

An unknown compound, X is thought to have a carboxyl group with a pKa of 2.0 and another ionizable group with a pKa between 5 and 8. When 75 mL of 0.1 M NaOH was added to 100mL of a 0.1 M solution of X at pH 2.0, the pH increased to 6.72. Calculate the pKa of the second group of X. ok...
15. ### Dissociation of glycine

Here's the problem how much of 5M KOH should be added to 1L of 0.1M glycine(pKa=9.6) at a pH of 9 until the pH reaches exactly 10? the answer in the back says 10mL. R-NH3(+) <-> R-NH2 + H(+) Here's the way I solved it. I figured out the number of moles of R-NH2 using the...
16. ### Acid indicator question

I don't undestand this question. How can i determine which will be the major component? HCl + Na2CO3 - > NaCl + H2O + CO2 Is it water?
17. ### Covalent bonds

I tried to google this but i found 2 substances that are covalently bonded. SiO2 and C6H12O6. Which one is the correct one? does hydrogen bonds count as covalent bonds? if not then it might be SiO2.... Anyone have any ideas? Thanks
18. ### Conjugate acid

I'm guessing the answer is a). I found a similar problem except if the bicarbonate was mixed with water instead. And the selections were: H3O(+), OH(-), CO3(2-), H2CO3 I think the answer to that question would be H2CO3 since it's asking for the conjugate acid which will be the form of...
19. ### Hard problem

I know this might be a chemistry question in a way, but they also have Gas Laws problems in a physics textbooks. I have no idea how to solve this problem. I used the pressure ratios to determine the percent increase in volume. But I'm stuck there. Please help. Thanks.
20. ### Gas Law problem

I don't seem to be able to get close to any of the choices given. Here's my work: 288 K = T P = 101.23 kPa 2% volume = water vapor Well the next day the pressure changes to 100.47 kPa at the same temperature. The volume changes by 101.23/100.47 = 1.008.... I'm stuck here.... Can...
21. ### Enthalpy question

I'm not really sure what the question is asking for. But my guess is they are asking for which one will output the most energy per mass of the reactants. If this is correct, then im guess the answer is b). If not can some one explain why? Thanks.
22. ### Another boiling point question

In the attachment, i think the answer is c). However c) has the same molecular weight as d) and they are both alcohols. Is it that c) is not symmetrical, thus more polar as compared to d) and which is why c) should have a higher boiling point due to the stronger intermolecular forces?
23. ### Atomic mass: Isotope question

How would you go about to solve this quesiton? I thought that to calculate this i had to set up an equation as: let x = the percentage of 85-Rb 84.91*x + 86.91*(1-x) = 85 x = 96%, but that's obviously wrong. How do i solve this question?
24. ### Ore Mining question

I know the clue in the question is that the ore is reduced by electrochemistry. However, which one is the right one? I don't know how the different metals in the question are refined. Can someone explain this to me? thanks.
25. ### Oxide coating question

i'm guessing the answer is d). I am really not sure about that though... Can someone explain to me what the correct answer is suppose to be and why? Thanks.
26. ### Boiling point question

I think the answer is e). I don't think it is ammonia because of the hydrogen bonding between nitrogen and hydrogen. This will result in a higher boiling point. This is the same with Hydrogen flouride and water. However, the two organic molecules i'm not sure. I assume that since the alcohol is...
27. ### Oxidation number

nevermind i found the answer. However, i just want to know, is hydrogen always assigned the oxidation number of 1+? As well, how come having a negative oxidation number means nitrogen is a strong oxidizer? Or is this wrong? Can someone please explain this to me? Thanks.
28. ### Change in energy = the heat absorbed by the calorimeter and the water?

I think the answer is d). Am i correct? Because the change in energy equals the heat absorbed by the calorimeter and the water. If not, can you please provide an explanation for your answer. Thanks
29. ### Total Energy Problem

The answer to the problem is a), the orbital speed will decrease but the total energy will become larger. How is this? It's kinetic energy has decreased and the gravitational potential energy should also have decreased from this equation GM(earth)m(object)/r where r has been increased, thus...
30. ### Why is the R resistance equal to the internal resistance

The answer to the attachment is if the R resistance was equal to the internal resistance. How was this determined? Please explain this to me because i have no idea how they can solve this. Thanks