DrBob 222

(C^2 + 14C + 49)/(C+7)= factor the numerator. [(C+7)(C+7)/(C+7)]= Now you finish.

17 years ago

Would you add 8 1/2 feet + 2 3/4 feet = ?? feet?

17 years ago

I don't know that you did anything wrong. How did you solve the quadratic? Did you use the quadratic formula?

17 years ago

I don't get the 0=0 step but your solution is correct for x = 1.5 and x = -0.3333.

17 years ago

First convert 50.6 g CH4 to mols. mols CH4 = 50.6 g CH4 x (1 mol CH4/16 g CH4) = ??

17 years ago

yes.

17 years ago

The flame color will be visible as a reddish violet color. The blue glass, typically a cobalt blue glass, will filter out extraneous colors, such as the intense yellow color of a sodium flame. The intense yellow color of the sodium flame will mask the pot...

17 years ago

All of that multiplied together is zero. (Because of the zero in the sequence)

17 years ago

A buffer is formed from a weak acid and its salt (conjugate base) OR a weak base and its salt (conjugate acid). For examples: acetic acid and sodium acetate (its the acetate that is the conjugate base part so it can be sodium acetate, potassium acetate. e...

17 years ago

And your question is a little confusing, too. ALL elements in the periodic table have a charge of zero when they are in their elemental state. You may be asking how to tell the charge on the ions. For the B group of elements, ONE of the possible ionic cha...

17 years ago

Clear the parentheses. r-6s+3+7r+5s+s+5=?? combine like terms.

17 years ago

Under the beaker with the tip of the inner blue cone of the burner just touching. However, I never like to heat a beaker directly (unless it's made of Vycor). I prefer to place the beaker on top of a wire gauze and heat the wire gauze. Beakers made of Pyr...

17 years ago

Most filter paper has a texture to it and any solid placed on it during the weighing may stick to the surface and not be transferred quantitatively to a vessel of choice. I assume this is the intent of the question. If I have misinterpreted, please clarif...

17 years ago

Sr(s) + NH4CO3(aq) ==> ppt + flammable gas. Wouldn't you expect the ppt to be SrCO3? And Sr + the water in the 1 M NH4CO3 solution must be H2 gas. Can you continue?

17 years ago

8x-(5x + 7)=17 remove parentheses. 8x - 5x -7 = 17 move -7 to the other side. 8x-5x = 17 + 7 combine terms 3x = 24 divide both sides by 3. 3x/3 = 24/3 x = 8. Check it. 8*8-(5*8+7)=17 64-(40+7)=17 64-(47)=17 64-47 = 17 17 = 17 It checks.

17 years ago

Lines are parallel if the slope is the same. They are perpendicular if the slopes multiplied = -1.

17 years ago

What do you not understand about collecting like terms?

17 years ago

And you think what?

17 years ago

GK is correct; the problem could have been worded more correctly. I assumed you were asking for the solution. Also, I note that I made an error in typing. It isn't 11.1 g CaCl2 but 1.11 g CaCl2.

17 years ago

yes. 80%X = 40 0.8X = 40 X = 40/0.80 = 50

17 years ago

Is that (-5/6)*x = -7/8 or (-5/6x) = -7/8

17 years ago

+1/3 ??

17 years ago

Shanta, please go to the top of the page and click on post a new question. Post a question in your name instead of an answer to another problem. Since there are three nitrate ion per mole of Al(NO3)3, then the nitrtion concn is ??

17 years ago

Remember the definitions. Molarity = # mols/L. and # mols = g/molar mass. How many moles CaCl2 do you have in 11.1 g CaCl2. That will be 11.1 g CaCl2/molar mass CaCl2. Then #mols = M x L. You have M and you have mols, calculate L.

17 years ago

Accuracy is how close the analyst is to the actual value. The precision is how close the repetitive values are to each other.

17 years ago

11/12-(1/3+1/4) = 11/12 - 1/3 - 1/4 = get a common denominator which is 12. 11/12 - 4/12 - 3/12 = Add the numerators to obtain 11-4-3 = 4 so the answer is 4/12 which reduces to 1/3 Check my work.

17 years ago

qH2O + qmetal = 0 qH2O = mass H2O x specific heat water x (Tfinal-Tinitial). qmetal = mass metal x specific heat metal x(Tfinal-Tinitial). Just plug in the numbers and solve for specific heat metal.

17 years ago

qH2O = mass water x specific heat water x (Tfinal-Tinitial). Then q/7.5 = heat of solid/gram if you use specific heat of water in joules (4.18 joules/g*C). Note that they tell you Tfinal-Tinitial = 6.2 degrees.

17 years ago

Yes, but it would be better if you posted your work. That way, if you have the wrong answer we will know what you did wrong. If you have the right answer we will also check that you came about the correct answer properly.

17 years ago

PV = nRT Since n is increased, what must happen to P.

17 years ago

yes

16 years ago

Divide Ksp of one by the other. [KspPbSO4/KspAg2SO4]=[(Pb^+2)(SO4^=)/(Ag^+)^2(SO4^=)]. Note (SO4^=) cancels and you are left with 2*10^-8/1.2*10^-5 = (Pb^+2)(Ag^+)^2 Plug in (Ag^+)^2 and solve for (Pb^+2), Check my thinking.

16 years ago

You have the answers mixed up with the number of the question to the point that the whole thing is confusing. The answer to the first question (H2SO4) is correct. The answer for what you have labeled 27A is blarney.

16 years ago

a) melting point - increases <b>OK</b> b) vapor pressure-increases <b>As the IM forces increase, it makes it harder for the molecules to escape to the vapor phase (the pressure of the gas over the liquid); therefore, the vapor pressure must decrease.</b>...

16 years ago

Would you explain what a stoic acid is. I don't know. Then I can answer your question.

16 years ago

I must admit that I have never heard of a stoic acid before. Thanks for the explanation. An ester is RCOOR' whereas an acid is RCOOH. What is attached to the RCOO- is the secret. If you attach a H atom, it is an acid. If you attach another R group (CH3 or...

16 years ago

You name the alcohol group first and the acid group second. The alcohol group in this case is methyl. Then you count the C atoms, including the C attached to the =O and name it as an -oate. So the name is methyl ethanoate (the acid CH3COOH is ethanoic aci...

16 years ago

Because the molecules are more randomly positioned.

16 years ago

Pb(OH)2 ==> Pb^+2 + 2OH^- Ksp = (Pb^+2)(OH^-)^2. pOH = -log(OH^-). You are given the pH, then 14-pH = pOH, and solve for (OH^-). Note carefully: Won't the (Pb^+2) be just 1/2 the (OH^-)?

16 years ago

M = moles/L So if the M = 0.00172, then the moles in a liter will be 0.00172. Since the problem tells you it is in 100 mL, then 1/10 that will be the moles that will dissolve in 0.100 L. To convert that to grams, moles = g/molar mass, then convert grams t...

16 years ago

I think the equations you want are as follows: AgI(s) ==> Ag^+ + I^- Ksp = (Ag^+)(I^-) = look up. Ag^+ + 2CN^- ==> Ag(CN)2^- Kf = [Ag(CN)2^-]/(Ag^+)(CN^-)^2 = look up.

16 years ago

The molecules are relatively far apart. In a liquid or a solid the molecules are much closer together. The molecules in a gas are much further apart UNLESS we are talking about LOW LOW temperatures OR HIGH HIGH pressure.

16 years ago

I don't think an ICE table is needed. You have the solubility at 0.00172 M so 1.72 x 10^-3 M is the # moles in 1 L, then 1.72 x 10^-4 is the # moles in 0.100 L, and grams = moles x molar mass.

16 years ago

There is no AgI in your final equation(and I'm not suggesting there should be); also, note that AgI as a solid has a molarity of 1 (by definition so the AgI-x has no meaning). (Technically it's the activity that is 1.) Also note that the problem states 15...

16 years ago

The 1.97 grams is extraneous information. You don't need it (as long as the problem says the solution is saturated AND there is a small amount of solid in the container). The (Pb^+2) IS 1/2 the (OH^-); i.e., 1/2*(OH^-)=(Pb^+2) So you know (OH^-) and you k...

16 years ago

1. What is the name of the ester formed from formic acid and methanol? ( I know formic acid equals methanoic acid(HCOOH) and we need to change "oic acid" to "-oate", but how about methanol? I had no ideas what to do with the alcohol...) <b> The alcohol pa...

16 years ago

Yes, it would be larger. Do you know why? It's important that you know why.

16 years ago

Read about the effect of ionic strength on solubility (the activity and the activity coefficient). The activity coefficient is a factor used to correct for non-ideal behavior of solutions. In connection with this, you will see reverence to the Debye-Hucke...

16 years ago

You misread my response or I misrepresented it---one or the other. Yes, CH3OH is methyl alcohol (the trivial name) or methanol if you name it by the IUPAC system. CH3- is the methyl group> The first part of the name is methyl because 1. its the alcohol (f...

16 years ago

I have tried to post sites but the board isn't posting.

16 years ago

Your equation looks great; however, the problem states that x is to equal to (Ag^+). You have it set up so that x = (Ag3PO4) = (PO4^-3) and (Ag^+) = 3x

16 years ago

No. The phosphate ion is 0.4762 (if your prof is a freak about significant digits perhaps this should be 0.48 since only 2 places are shown for the Ksp in the problem. The problem states that x = (Ag^+) [in fact it is repeated in the problem] and what you...

16 years ago

There is nothing wrong with the equation except that when you solve for x you get what? What did you let x stand for? It looks to me as if you let x stand for the solubility of Ag3PO4 and Ag^+ is then 3x. So when you solve your equation, you will get x TH...

16 years ago

You didn't square the OH^-

16 years ago

I think so. Look up Ksp in your set of Ksp tables and see how close that comes. I have an old quant book (about 15 years old) that shows 2.5 x 10^-16.

16 years ago

Try something here. Work the problem as (3x)^3(0.476) = 1.3E-20, solve for x, then multiply by 3 and that will be Ag^+. NOW, try letting Ag^+ = x (instead of 3x). How will the equation look then? Will it be (x)^3(0.476) = 1.3E-20. Solve that and see if x...

16 years ago

I will try to post those sites under a new post. Look at the top for them.

16 years ago

The sites won't post.

16 years ago