Homework Help

Washing soda is added to hard water to allow soap to lather. A brand of washing soda contains partially hydrated sodium carbonate solid. A 0.300 g sample completely reacts with 20.0 mL of 0.250 M hydrochloric acid. a) What mass of sodium carbonate was present? b) Calculate the percentage by mass of sodium carbonate in the washing soda. Please. Any help would be appreciated! How do I do this question? Would anyone be able to give me some hints/advice on how to tackle this question?

On a horizontal test track two motors (jet and rocket) are tested. Starting from rest, the rocket motor was accelerated constantly for half the distance of the track and ran the other half at a constant speed. Next, a jet motor was started from rest and finished the whole track with constant acceleration for the entire distance. Both motors covered the same distance in the same time. Show that the ratio of the acceleration of the jet motor to rocket motor is given by: aj/ar = 8/9 I wrote two equations for the distance of each motor. For rocket: x = 1/8 ar*t^2 + v*t/2 and since v*t/2 = ar*t^2/4 we get x = 1/8 ar*t^2 + v*t^2/4 and for the jet motor: x = 1/2 aj*…

The concentration of sodium hydroxide in waste water from an alumina refinery was found by titrating 20.00 mL aliquots of the water against 0.150 M hydrochloric acid, using phenolphthalein as indicator. The average titre of several titrations was 11.40 mL. a) Why is an indicator used? What can I say to make a well response answer? I'm guessing I should use the words "end-point" and "equivalence point" and how they have to be relatively equal for the experimenter to obtain accurate results. But how can I explain in words why this is the case? Here is the answer I have written: "An indicator is used in the titration so that when the titration reaches a point where …

i would like to do my design project of an oven controller/ my idea is that when the pot burns at a certain temperature that can cause fire or damage the circuit breakershould trip

Can't paste picture into message, so displaying link to get to picture.

I'm not quite sure how to do arrow pushing for these molecules? I know they are probably easy, but I don't quite understand. Link to the diagrams (there are 3 questions): http://i10.photobucket.com/albums/a120/SakamotoKumiko/organochem.jpg I'm not sure if these diagrams are correct because my friend said some of these are impossible, but that is how my lab TA drew them. For the last reaction, I thought I had to draw 2 different arrow pushings for both products but my friend said no, you can do it in one step. I'm not sure. I know I'm not the smartest, but I would be nice if you can help. Thank You In Advanced!

A student titrated an aliquot of standard sodium carbonate solution with hydrochloric acid in a burette. State whether the concentration determined for the hydrochloric acid would be likely to be higher, lower or unchanged compared with the actual value if the student had previously washed with water, but not dried, the following apparatus: a) the pipette used to deliver the aliquot of sodium carbonate solution b) the flask containing the aliquot c) the burette. Any help to the above questions would be immensely appreciated!

What volume of 0.100 M sulfuric acid would be required to neutralise a solution containing 0.500 g of sodium hydroxide and 0.800 g of potassium hydroxide? Any help showing the step-by-step working out to the above problem would be appreciated!

What mass of sodium sulfate is produced when 25.0 mL of 0.100 M sulfuric acid is added to 20.0 mL of 0.15 M sodium hydroxide solution? [latex]n=cV[/latex] [latex]n(H_{2}SO_{4})=0.100*0.0250=0.00250=2.50*10^{-3} mol[/latex] [latex]n=cV[/latex] [latex]n(NaOH)=0.15*0.0200=0.0030=3.0*10^{-3} mol[/latex] [latex]\frac{n(H_{2}SO_{4})}{n(NaOH)} =\frac{1}{2}[/latex] [latex]n(H_{2}SO_{4})[/latex] required [latex]= \frac{1}{2} * (3.0*10^{-3}) = 0.0015 = 1.5*10^{-3} mol[/latex] [latex]n(H_{2}SO_{4})[/latex] is in excess by [latex](2.50*10^{-3}-1.5*10^{-3}) 1.0*10^{-3} mol[/latex]. NaOH is the limiting reagent. [latex]\frac{n(Na_{2}SO_{4})}{n(NaOH)} = \frac…

A person looks out of the window and sees a tennis ball that appears and disappears twice: first as it rises up past the top of the window and then again as it falls bellow the bottom of the window. The height of the base of the window to the top of the window is y. The total time he sees the ball is t. Show that the height (measured relative to the top of the window) that the ball reaches is given by h=1/2g(2y/t - gt/4)^2<br />How do you solve this? I tried it for an hour and can't figure it out.

I performed an experiment in my physics lab course recently involving the use of a scintillator to count the number of radioactive decays that occur over a certain period. For example, I placed radioactive sodium-22 in front of the scintillators and observed a certain number of gamma decays in ten seconds. In my analysis, I need to estimate the uncertainty of this measurement. Now, I know radioactive decay is a random process, so in ten seconds I may observe 107 decays, or 95, or 111. As I take larger samples over longer intervals, the random variance becomes less significant compared to the total count. My question is: how do I estimate the random variance in the…

Let V be the vector space of all real-valued continuous functions. t, e^t, sin(t) are in V. Is t, e^t, sin(t) in V linearly independent? My answer is yes. However, how can I prove it which is that which do I have to show or can I just say the def of linear independent?

i did an experiment on solubility product constant which involves titration of concentrated calcium hydroxide and HCl at constant temperature and we did titration to find the Ksp. but now i can't figure out what is the relationship between reaction of Ca(OH)2 used to neutralised HCl with Ksp definition. does it means that in the calcium hydroxide solution, Ca(OH)2 the sparingly soluble salt is not completely ionised and only the ions are able to react with HCl? also since Ca(OH)2 is used, will the equilibrium of saturated solution be affected (Le Chatelier"s Principle)?

Suppose that the solution set to a linear system Ax = b is a plane in R^n with vector equation x = p + su + tv , s, t ∈ R . Prove that p is a solution to the nonhomogeneous system Ax = b , and that u and v are both solutions to the homogeneous system Ax = 0 . (Hint Try choices of s and t). Should I start from A(p + su + tv) = b? If yes, what should I do from here? If no, where should I start?

Hello Everyone, I have been assigned to write a HYPOTHETICAL research proposal for a graduate level Biochemistry class. I have been racking my brain for possible topics, as well as scouring dozens of journals but I cannot seem to find any that will provide me with a working hypothesis that could utilize reasonable biochemical techniques. If you have come accross any recent topics/papers in your travels that have any unanswered questions that could be easily solved I would really appreciate it if you would post them below. Thank you!!! I just need a few ideas to maybe get me in the right track.

sorry, dumb question.

Hey guys, Just joined this forum; I'm studying for a microbiology exam coming up in May, and I have to say, I'm having a LOT of trouble memorizing the different kinds of media, e.g.: selective, all purpose, enriched, differential. Does anyone have a good way of remembering? Also, my bigger issue, is remember all the different aspects of selective and differential media. We have to memorize the ingredients, what they select for, what their pH indicator is, and the differential reactions of the following: Blood Agar MacConkey Agar Eosin Methylene Blue Agar Mannitol Salt Agar Sabouraud Dextrose Agar Anybody know a good way of remembering all of this? …

Hey guys been losing alot of marks for my discussion on my prac reports, as i tend to talk too much irrelevant stuff like errors (which should be in error analysis) could someone please tell what i should include/talk about in a discussion? i know to talk about the results but i usually end up not finding enough stuff to talk about... If any of you have some examples that you could upload, that would be great as well Our next prac writeup is to to "use the conservation of energy laws to investigate the effect of the mass of the object moving down an incline and the vertical height of the incline on the velocity of the object at the bottom of the incline". So …

Hi guys, i was hoping someone might be able to point me in the right direction on a restriction mapping problem i have to do. I have 2 plasmids named 18 and 18L. They are both clones from a pBluescript vector with a cDNA insert, inserted at the MCS. This region was restricted with Apa1 and EcoR1 and then put through an agrose gel separation. From this I have (i think) constructed a restriction map for both. Now, the EcoR1 site is supposed to be replicated at each end, but in the 18L plasmid one of them is missing and the MCS is also shorter: 18 is 5.8Kb and 18L is 5.0Kb with a 'missing' EcoR1 site. I have to consider the relationship between these two plasmids. Being a…

Suppose now we have two acids A. 10 cm3 of 1M sulphuric acid B. 10 cm3 of 1M hydrochloric acid I just want to ask how should I calculate in order to know which acid has a higher concentration of H+

I was just wondering if anyone knows the formula to convert an absorbence reading from a spectrometer reading to the amount of protein in micrograms.

Hi Does anyone know why finding the sizes and locations of restriction enzyme sites is useful? And also why finding the sequence of an intron would be useful? Or else a really good, clear site with the information would be awsome. Thanks!

Hey everyone, I am in Chemistry 11 and we've just started learning about ion concentration and titration. I'm not sure if I did this correctly but I need help with this one question: "What is the concentration of each ion in the solution formed when 94.5 g of nickel (III) sulphate is dissolved into 850.0 mL of water?" For the equation I came up with: Ni2(SO4)3 + 6H20 → 2Ni + 6OH + 6H + 3SO4 Is this this correct? Then I assume you take 94.5/.85L to get the molar concentration and you use the concentration and use stoichiometry to find the concentration for each of the ions? Thank you in advance!

We cannot pass beyond body to a further kind, as we passed from length to surface, and from surface to body. For if we could, it would cease to be true that body is complete magnitude. We could pass beyond it only in virtue of a defect in it and that which is complete cannot be defective, since it extends in every direction. Now bodies which are classed as parts of the whole are each complete according to our formula, since each possesses every dimension. But each is determined relatively to that part which is next to it by contact, for which reason each of them is in a sense many bodies. But the whole of which they are parts must necessarily be complete, and mus…

1) Let u and v be nonzero vectors in a vector space V. show that u and v are linearly dependent if and only if there is a scalar k such that v = ku. Equivalently, u and v are linearly independent if and only if neither vector is a multiple of the other. 2) Let S = {v1, v2, ..., vk} be a set of vectors in a vector space V. Prove that S is linearly dependent if and only if one of the vectors in S is a linear combination of all the other vectors in S. For these two questions, I know I have to prove them in both directions because of "if and only of". However, how to approach this problem? what Thms or definition should I use to prove them? 3) Let S = {v1, v2, ...…