Could you please explain how you got that answer? I'm getting confused with all of the numbers in front of the chemical names.
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Homework Help Thread
- Thread starter iKitsune
- Start date
Sure. Matter is niether created nor destoyed. You broke this rule in your equation.
In the reactants, you have 1 Cu (copper), 2 Cl (chlorine) and one Al (aluminum)
In the products, you have 3 Cl, one more Cl than in the reactants, so you created a Cl atom out of nowhere. Which is wrong since you can't just create an atom.
You have to balance the equation to 2 Al + 3 CuCl2 --> 2 AlCl3 + 3 Cu
I FUCKED UP HERE BEFORE> There are 2 Al on both sides, 3 Cu on both sides, and 6 Cl on both sides.
I can't just change the subscript in the reactant to CuCl3 since that would have a 1- charge. I can however change the number of CuCl2 (or any other reactant and product) needed.
You have to balance the equation so the reactants and the products on each side are the same. it is logically impossible to create substance out of nothing, and likewise turn a substance into absolutely nothing.
for example, lets say (and just using random letters, not real chemicals)
Ax + Bf2O3 --> Ax2O2 + Bf6
My process has Ax doubling and Bf tripling. So we have to balance it out. However, the golden rule is "what you do to one side, you do to the other.
[6]Ax + [3]BF2O2 --> [3]Ax2O2 + BF6
we didn't change the equation, we just logically made it correct.
i hope that helps (and is correct)
You have to balance the molecules and keep things at neutral charge. If it reacts, there should (probably) be only one way for the product to be neutrally charged.
In that reaction, Al and Cl combined to make Aluminum chloride. It has to be AlCl3 since Al has a charge of 3+ and Cl has a charge of 1-
You need for the Aluminum chloide to be neutral so it needs to have 3 Cl to be neutral (since the charge of 3 Cl's is -3 and one Al is +3)
2 Al + 3 CuCl2 --> 2 AlCl3 + 3 Cu
I FUCKED UP HERE BEFORE> There are 2 Al on both sides, 3 Cu on both sides, and 6 Cl on both sides.
I don't think this rule applies in chemistry as it does in math. I'll think of an example and edit
Yeah, this isnt always true as seen here:
C4H10 + O2 --> CO2 + H2O
When I balance it, i get
2C4H10 + 13O2 --> 8CO + 10H2O
Although i doubled the amount of butane in the reactants side, I didn't double anything in the products. (I octupled the Carbon Monoxide and decupled the Water)
You pretty much just have to think logically about what must have happened. In that case, you had an ionic compound (CuCl2) and a pure element (Al) as your reactants. What could possibly happen between them? Well, since you only have three elements, two of them switching places seems most logical. But which ones? To answer that, look at them in their ionic forms. When copper's an ion, it'll be positive, when Chlorine's one, it will be negative, and when Aluminum's one, it'll be positive.
Now then. Elements can only replace or "kick out" elements that have the same charge (positives will only replace other positives; negatives replace negatives). In this case, you only have one negative-ion, so that's no good. Thus, the two positive ions must be replacing each other. So, just write that out, and you get the formula that was described.
The same thing applies for stuff like double replacement reactions--if you have two ionic compounds reacting with each other, then the positive ions in each will be replacing each other, and the negatives will be replacing each other.
Combustion can't really be predicted in that way, but the formula always follows the same pattern, so you mostly just have to worry about balancing the equation here.
Anyway, once you've figured out what the products must be, then you just balance them the same way as has been done--first use subscripts on the individual ions to balance out and even their charges, then put in coefficients to balance out the amounts of atoms of each element on both sides of the equation.
Does anyone know a thing about complex analysis? I don't want to make an idiot out of myself by posting something that nobody will be able to answer.
This bloody subject is giving me nightmares!
This bloody subject is giving me nightmares!
X-Act, if you are reading this, please impart your statistical knowledge?
Okay, Last question of a study paper for Stats. Please don't outright tell me the answer, I already have it and I won't learn anything. Just help out on how I would tackle the question. Please and thanks. :)
QUESTION SIX : Designing a New Hotel
A new hotel for Statsmod Enterprises is to have only deluxe and standard rooms. In designing the new hotel, the following constraints need to apply:
• The maximum number of rooms is 65.
• The building cost budget for the rooms has a maximum of $3 million. Building costs are $45 000 for a standard room and $60 000 for a deluxe room.
• When the number of standard rooms (x) is such that 10m < x ≤ 10(m + 1), then the number of deluxe rooms (y) is such that y ≤ 5(m + 1), where m = 0, 1, 2, 3, 4.
The profit for deluxe rooms is 40% greater than that for standard rooms.
(a) Assuming that all rooms are occupied, find the number of each type of room that should be built to ensure maximum profit.
A grid is provided on page 26 of the Answer Booklet to help you answer this question.
(b) Statsmod Enterprises wants to ensure maximum profit and build the maximum number of 65 rooms, but cannot do so within the $3 million building cost budget.
What is the smallest required increase in this budget?
(c) Suppose the mean occupancy rate for deluxe rooms is 60% and that all three constraints still apply.
While still ensuring maximum profit, calculate the occupancy rate for standard rooms, which will give more than one solution for each type of room that should be built. Clearly state all of these solutions.
Okay, Last question of a study paper for Stats. Please don't outright tell me the answer, I already have it and I won't learn anything. Just help out on how I would tackle the question. Please and thanks. :)
QUESTION SIX : Designing a New Hotel
A new hotel for Statsmod Enterprises is to have only deluxe and standard rooms. In designing the new hotel, the following constraints need to apply:
• The maximum number of rooms is 65.
• The building cost budget for the rooms has a maximum of $3 million. Building costs are $45 000 for a standard room and $60 000 for a deluxe room.
• When the number of standard rooms (x) is such that 10m < x ≤ 10(m + 1), then the number of deluxe rooms (y) is such that y ≤ 5(m + 1), where m = 0, 1, 2, 3, 4.
The profit for deluxe rooms is 40% greater than that for standard rooms.
(a) Assuming that all rooms are occupied, find the number of each type of room that should be built to ensure maximum profit.
A grid is provided on page 26 of the Answer Booklet to help you answer this question.
(b) Statsmod Enterprises wants to ensure maximum profit and build the maximum number of 65 rooms, but cannot do so within the $3 million building cost budget.
What is the smallest required increase in this budget?
(c) Suppose the mean occupancy rate for deluxe rooms is 60% and that all three constraints still apply.
While still ensuring maximum profit, calculate the occupancy rate for standard rooms, which will give more than one solution for each type of room that should be built. Clearly state all of these solutions.
Well, if you could tell me what the m stands for in the equations you posted (mean?) I'd be glad to (try) to help you with a and b. But c is screwed.
Okay, I managed to figure out a) and b) It was a lot easier than I first realised.
This is what I got.
Let x = number of standard rooms
Let y = number of deluxe rooms
The constraints are:
• x + y ! 65
• 45 000x + 60 000y ! 3 000 000 when simplified gives 3x + 4y ! 200
• when 0 < x ! 10 y ! 5, 10 < x ! 20 y ! 10, 20 < x ! 30 y ! 15, 30 < x ! 40
y ! 20 and 40 < x ! 50 y ! 25.
The profit is P = 1.0x + 1.4y
To ensure maximum profit, x = 40 and y = 20 that is 40 standard rooms and 20 deluxe rooms should be built.
And I drew a graph, though I'm not going to scan it haha.
Then, continuing on from that, b goes something like this:
Take (41, 24), as it gives the maximum profit P and it gives a cost ($000) = 45(41) + 60(24) = $3,285,000 so smallest required
increase in the budget is $285,000.
Niklink, you're right. C is out of my knowledge at the moment, good thing I have 28 days before my exam to sharpen up.
This is what I got.
Let x = number of standard rooms
Let y = number of deluxe rooms
The constraints are:
• x + y ! 65
• 45 000x + 60 000y ! 3 000 000 when simplified gives 3x + 4y ! 200
• when 0 < x ! 10 y ! 5, 10 < x ! 20 y ! 10, 20 < x ! 30 y ! 15, 30 < x ! 40
y ! 20 and 40 < x ! 50 y ! 25.
The profit is P = 1.0x + 1.4y
To ensure maximum profit, x = 40 and y = 20 that is 40 standard rooms and 20 deluxe rooms should be built.
And I drew a graph, though I'm not going to scan it haha.
Then, continuing on from that, b goes something like this:
Take (41, 24), as it gives the maximum profit P and it gives a cost ($000) = 45(41) + 60(24) = $3,285,000 so smallest required
increase in the budget is $285,000.
Niklink, you're right. C is out of my knowledge at the moment, good thing I have 28 days before my exam to sharpen up.
Kind of an uncommon subject, I know, but I need help in my Music Theory class. The question is quite simple, if you know what is being talked about. The teacher usually lectures the class, does an example, then assigns homework.
Currently we're working with voice leading/part writing. On the homework assignment they give us a grand staff with the soprano and bass notes already filled in, and they're all root position. We need to analyze the chord structure, and on this assignment there's only tonic, sub dominant and dominant. We have to fill in the tenor and alto voices with notes from the chords.
What I don't remember is a rule about leaps. I remember something being said about leaps that are a 4th or more, but I don't remember what was said exactly. I think I recall something about having to go back in the opposite direction after the leap? What if you're going to the last note, can you not use a leap of a 4th or larger? Or can you not use leaps that large at all? O_O confused..
Currently we're working with voice leading/part writing. On the homework assignment they give us a grand staff with the soprano and bass notes already filled in, and they're all root position. We need to analyze the chord structure, and on this assignment there's only tonic, sub dominant and dominant. We have to fill in the tenor and alto voices with notes from the chords.
What I don't remember is a rule about leaps. I remember something being said about leaps that are a 4th or more, but I don't remember what was said exactly. I think I recall something about having to go back in the opposite direction after the leap? What if you're going to the last note, can you not use a leap of a 4th or larger? Or can you not use leaps that large at all? O_O confused..
I would think that leaps of a 4th or higher are allowed; the example that sticks out is the first line of "somewhere over the Rainbow", where the syllables in "somewhere" are an octave apart. Also, for a lot of church music, the "Amen" at the end is a IV-I chord progression and so I would think that it would be allowed at the end of a piece. I would also think that this could apply to choir writing, however, I was never taught choir writing when doing Music.
I would think that the chord structure is would be the type of chord that is used, e.g. IIIb for a chord where the root is the 3rd not of the chord and the chord is arranged so that it is second in the chord (for C Major, this would be GEB), and so you could fill in the Staff for the Tenor and Alto parts in this way.
@Mountain Dewgong, I would have thought for part c you would multiply the profit for the Deluxe rooms by 0.6 (because they are only generating profit 60% of the time, or 0.6, assuming that the standard rooms are always full) and then just do the calculation from there
Hope that helps! ^__^
I don't think there are any concrete rules about large leaps, but you should avoid any leaps larger than a 5th if at all possible, and really a leap of a 5th is pretty large, so if you can avoid using that, it would be for the best. If the soprano and bass are all root position, there probably will be large jumps in those lines, but that doesn't mean that you can't work around with the inner voices and get most of their movements to be seconds and thirds. Generally the soprano lines will have much larger leaps, and the inner voices try to keep the jumps smaller.
from I-IV, for example, your soprano and bass will be I, and you can have tenor be V and soprano be III. When the chord changes, the soprano can go down to I (which is the V of IV), and tenor can go from V to VI (III of IV). These are only thirds and seconds, not a problem at all
from I-IV, for example, your soprano and bass will be I, and you can have tenor be V and soprano be III. When the chord changes, the soprano can go down to I (which is the V of IV), and tenor can go from V to VI (III of IV). These are only thirds and seconds, not a problem at all
K, guys, I need you to check my work on this physics problem and help me out a bit on part 2.
1. A 2.0 kg ball is moving to the left with an initial velocity of 10 m/s when it strikes a 0.5 kg ball moving to the right at 20 m/s.
1. A 2.0 kg ball is moving to the left with an initial velocity of 10 m/s when it strikes a 0.5 kg ball moving to the right at 20 m/s.
a. If the collision is perfectly elastic, find the final speed and direction of each ball.
b. If the collision is perfectly inelastic, find the final speed and direction of each ball.
Now we use the formula in which Ball 2 is at rest:
v1f = v1i * (m1-m2)/(m1+m2) = -30 * (1.5/2.5) = -18 m/s, or 18 m/s left
v2f = v1i * (2m1)/(m1+m2) = -30 * (4/2.5) = -48 m/s, or 48 m/s left
So what exactly do I do for a perfectly inelastic collision?
Can someone help me with some electrochemistry? It's a simple question...
Why do electrochemical cells work? What causes the electrons to from the anode to travel to the cathode? I'm pretty good at explain how they work, but I'm stumped on why they even happen.
Can you also explain Electrolytic Cells? My teacher never went over it inclass and it's on my test tomorrow. :( I tried using the textbook / wikipedia, and I'm so lost... How do you take electrochemical cell and make it an electrolytic cell?
Why do electrochemical cells work? What causes the electrons to from the anode to travel to the cathode? I'm pretty good at explain how they work, but I'm stumped on why they even happen.
Can you also explain Electrolytic Cells? My teacher never went over it inclass and it's on my test tomorrow. :( I tried using the textbook / wikipedia, and I'm so lost... How do you take electrochemical cell and make it an electrolytic cell?
You answered a) and b) yourself.
Question c) is very unclearly worded... I'm not understanding what he intends to say when saying "will give more than one solution for each type of room that should be built".
In an inelastic collision, kinetic energy is not conserved, but momentum is conserved, and the two balls will stick together. Since the balls stick together, they will have the same final velocity. It's actually much easier than elastic collisions.
m1*v1+m2*v2 = (m1+m2)vf
EDIT I also don't think you did the elastic collision right. If a ball going to the left at 10 m/s hits a ball going to the right, how would it bounce off and move faster than it was in the first place? It should lose speed, not gain. EDIT actually disregard this, it could gain speed if the ball it bounced off of had a greater momentum, which is the case in this problem. =x
Err, I think I know where I made my mistake: I forgot to reverse the Galilean transformation. So we add 30 m/s to each of them, I guess...
For the 2 kg ball, its 12 m/s right.
For .5 kg ball, its 18 m/s left.
This is the basics: it's like a reversed redox (reduction/oxidation) reaction. The reduction reaction occurs on the + and the oxidation on the -.
If you electrolyze a salt solution using electrodes made from Pt or C, they won't participate in the reaction, otherwise they may (together with the participating ions and H2O). Example: you have a solution of Na+ + OH- and you have graphite electrodes. You will have to look up the least electronegative reductor first; this is OH-(at+0,40). Our most electronegative oxidator is water, at -0,83.
+: 4 OH- -> O2 (g) +4 H2O (l) +4e-
-: 2H2O (l) +2e- -> H2 (g) + 2 OH-
Sometimes the electrodes may react (if they are not carbon or platinum or something like that). If we have a solution of Zn2+ and 2Cl- with Zn (s) electrodes, we get: Zn (s) -> Zn2+ + 2 e- and Zn2+ +2 e- -> Zn (s)
actually, you only subtracted 20, so you would only add 20 back. Otherwise, you are right.
Actually, my previous observation was incorrect, I just said something dumb without actually doing the math to check the solution (because I hate elastic collision problems but that shouldn't be an excuse), so I apologize if that made you do extra work when you made your corrections.
yesMr. Dreavus said:
That is the equation of a particular ellipse, the one passing through the points (4,0), (0,3), (-4,0) and (0,-3).
Sorry to bump this thread, but I need help with this question.
What is the derivative of y = xe^(-kx). The answer says it's [e^(-kx)][-kx+1] but I seem to get instead of -kx but -k^2x which is really frustrating me. Essentially, I divided the x and the e^(-kx) with the power rule, and with the chain rule, I could get the derivative of e^(-kx). I get
x d/dx e^(-kx)+ [e^(-kx)] d/dx x
which I believe is right.
But when I calculate it, I get:
d/dx e^(-kx) = [e^(-kx)][-kx] and then that's multiplied by x, so it equals [e^(-kx)][-(k^2)x]
and the other side is just e^(-kx) as the derivative of x is 1.
So when I put these two things together, I get [e^(-kx)][-(k^2)x+1], which according to the answer key is wrong.
Anyone want to help?
What is the derivative of y = xe^(-kx). The answer says it's [e^(-kx)][-kx+1] but I seem to get instead of -kx but -k^2x which is really frustrating me. Essentially, I divided the x and the e^(-kx) with the power rule, and with the chain rule, I could get the derivative of e^(-kx). I get
x d/dx e^(-kx)+ [e^(-kx)] d/dx x
which I believe is right.
But when I calculate it, I get:
d/dx e^(-kx) = [e^(-kx)][-kx] and then that's multiplied by x, so it equals [e^(-kx)][-(k^2)x]
and the other side is just e^(-kx) as the derivative of x is 1.
So when I put these two things together, I get [e^(-kx)][-(k^2)x+1], which according to the answer key is wrong.
Anyone want to help?
Let's try using the division rule, though I foresee this getting messy anyways.
xe^(-kx) = x/(e^kx)
So immediately we have f(x) as 'x' and g(x) as 'e^kx'
(f/g)' = (gf' - fg')/(g^2)
So we have (e^kx - kx*e^-kx) / (e^kx)^2
Factor out e^kx from the top and from the bottom to get [(e^kx)(1-kx)] / [(e^kx)(e^kx)]
Now divide the numerator and denominator by e^kx.
So we get (1-kx)/(e^kx).
This is the same thing that your book says, just written a different way via basic exponent rules.
xe^(-kx) = x/(e^kx)
So immediately we have f(x) as 'x' and g(x) as 'e^kx'
(f/g)' = (gf' - fg')/(g^2)
So we have (e^kx - kx*e^-kx) / (e^kx)^2
Factor out e^kx from the top and from the bottom to get [(e^kx)(1-kx)] / [(e^kx)(e^kx)]
Now divide the numerator and denominator by e^kx.
So we get (1-kx)/(e^kx).
This is the same thing that your book says, just written a different way via basic exponent rules.