Answers by visitors named: GK

I think I have seen these questions before. The net ionic equations look OK. The following are comments on the explanations: #1) OK #2) There fewer ions in the products (not reactants) which accounts for the decrease in electrical conductivity. #3) We sta...

17 years ago

The equation I would set up based on the information given is: 2.56g Benz. Acid /100cm^3 water = 1.00g Benz. Acid / x cm^3 Without the units, 2.56 /100 = 1.00 / x Solve the above equation for "x" to get the minimum volume of water in cm^3 that would be ne...

17 years ago

This is not a chemistry question and we don't have access to page 86 of the unnamed textbook. The best advice is offered right in the question: Read the Bead Bar Consultant Information .... etc.

17 years ago

The solid must have high solubility at high temperature and much lower solubility at low temperature in the solvent or mixture of solvents chosen. The solid is dissolved at high temperature in the least volume of solvent, then cooled off. Unless the solut...

17 years ago

The salt contains the conjugate base or acid of the corresponding acid or base on the list. Since most buffers are combinations of a weak acid and its conjugate base, or a weak base and its conjugate acid, the combination of the salt and the related acid...

17 years ago

Here are the two partial chemical equations with one formula for you to fill in in each one: Please note: *SO2 in a water solution is equivalent to sulfurous acid, H2SO3 -------------------- NaOH + HBr ---> NaBr + ______ 2NaOH + SO2 ---> Na2SO3 + ______

17 years ago

Acetic acid can be neutralized with sodium bicarbonate. The products of neutralization are H2O, CO2, and sodium acetate, NaC2H3O2. Carbon dioxide,CO2, escapes as a gas. Sodium acetate dissolves in water. So, the excess of acetic acid is first converted to...

17 years ago

It is great working with you again DrBob. I answered this same question on another network that allows links. The student was kind enough to provide a link to the procedure with a diagram, otherwise I would not have been able to visualize the experiment....

17 years ago

Do a Google search using as your search phrase: partial molar enthalpy of solutions. The very first result will be a PDF file that will addresses your topic. I hope you are familiar with partial derivatives and the laws of thermodynamics sufficient...

17 years ago

Comment: Lab questions are difficult to judge because we do not know what the instructions were, how close they were followed, and what assumptions can be made in answering the post-lab questions. Here is my take on the questions on the determinati...

17 years ago

Thank you, DrBob. JenniferT deserved a correct answer.

17 years ago

The major product is 1-cyclohexenol or 1-hydroxycyclohexene. The tautomeric form is cyclohexanone.

17 years ago

Since the solutions are 1.0M, E(cell) equals the difference of the standard reduction potentials. In more complicated cases (molar concentrations not equal to 1.0M) you would have to use the Nernst Equation.

17 years ago

This question has already been posted and answered, but I have a comment on the last part. The reason the spectral color lines are different for each element is that the photons produced by the dropping of electrons to lower energy levels within an atom a...

17 years ago

1. A flame heats the sample and may produce a flame color that helps us detect the presence of a certain element. Some elements cause the flame to glow a certain color which tells us that element is present in the sample. For example, a very bright yellow...

17 years ago

1. The weight loss from 45.850g to 45.351g is the mass of oxygen, O2, gas released. The molar mass of O2 is 16.00x2 = 32.00g. This information should enable you get the moles of O2. 2. The volume of O2 = volume of water displaced. volume = mass/density. T...

17 years ago

Electrical potential is the force experienced by a unit test charge at a particular point. In this case that potential on the test charge is generated by the positive and the negative charges placed in the two corners of the square. There are two possible...

17 years ago

To get the coordinates of each point you can use: (x1, y1) ---> x1=r1*cosA, y1=r1*sinA (r1 = 1.2km, A = 33deg) (x2, y2) ---> x2=r2*cosB, y2=r2*sinB (r2=2.0km, B = 75deg) The displacement is: d = sqrt[(x2-x1)^2 + (y2-y1)^2] The direction of the resultant,...

17 years ago

The velocity of the particle increases by a constant 5 m/s each second in the same direction. If we graph velocity v. time, we get a straight line with a positive slope. This line goes through the origin.

17 years ago

This question has already been answered. Enough hints have been given in that answer to complete it yourself. The assistance provided here is designed to help you learn enough to answer your own questions.

17 years ago

The graph of volume v. pressure should be a hyperbola since the volume and pressure of a gas vary inversely. However a small variation in pressure (i. e. 100cm H2O / 13.55 H2O/cmHg=7.4 cm of mercury which you have) would produce a near straight line with...

17 years ago

The vocabulary and symbols in this question are covered in any chemistry textbook with many examples. You should look them over.

17 years ago

The number of neutrons is: (mass number) - (atomic number) The mass number of the most common isotope of phosphorus is 31 (the rounded off atomic mass). I will let you look up the atomic number and do the subtraction.

17 years ago

The question is asking you (in a confusing way) to compare ionic bonds to INTERMOLECULAR attractions (attractions between neighboring molecules). The answer to that should not be much of a challenge. Consider the melting point of an ionic solid like sodiu...

17 years ago

The least common multiple of 3 and 2 is 3x2=6 For each of the two elements, valence x subscript = 6 Based on that, the formula would be A2B3

17 years ago

Atmospheric conditions are also called weather.

17 years ago

Na: 1s^2, 2s^2, 2p^6, 3s^1 or, Na: [Ne] 3s^1 Sr: 1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 4s^2, 3d^10, 4p^6, 5s^2 or, Sr: [Kr] 5s^2 P: 1s^2, 2s^2, 2p^6, 3s^2, 3p^3 or, P: [Ne] 3s^2, 3p^3

17 years ago

That depends on the design of the machine. Any design will violate at least one law of thermodynamics (1st, 2nd, or 3rd). Having said that, most people think that it is the 1st or 2nd law that would have to be violated in designing a perpetual motion mach...

17 years ago

a) [Ne] 3s^2, 3p^4 shows (2+4)=6 valence electrons. That is Group VI (O, S, etc.) in the "p-block" (last 6 columns) b) [Kr] 4d^10, 5s^2, 5p^2 shows (2+2)=4 valence electrons, Group IV (C, Si, etc.) in the "p-block" (c) [Xe] 4f^14, 5d^10, 6s^2, 6p^5, 7 val...

17 years ago

Write rate law expressions? 2NOCl(g) --> 2NO(g) + Cl2(g) rate=k[NOCl]^2 based on the Law of Mass Action. That is not necessarily the actual rate law, which must be determined by experiment. The effect of pressure depends on how the pressure is increased....

17 years ago

This does not look like a complete question. How many grams of Fe2O3 are there?

17 years ago

Limestone can be heated in a furnace to convert it to quicklime which can be mixed with water to make lime (calcium hydroxide). Calcium hydroxide cam be mixed with sand and water to make lime mortar. Cement, which contains lime and other ingredients can a...

17 years ago

Each electrode defines a half cell. Two half cells make up a complete electrochemical cell. The assignment of 0.00 volts for the hydrogen electrode potential is arbitrary. It was chosen because it is easy to construct, it behaves in a consistent, reproduc...

17 years ago

When an electron moves closer to the nucleus, its potential energy decreases.

17 years ago

#1) Your answer is OK. It can be rewritten as 1.201x10^24 carbon atoms. #2) If you have 3.67 mol H2SO4, mols of hydrogen=(3.67)(2)=? mols of sulfur=(3.67)(1)=? mols of oxygen=(3.67)(4)=? Multiply each of the answers above by Avogadro's number, 6.02x10^23.

17 years ago

All oxidations are exothermic

17 years ago

Yes, melting ice is a physical change.

17 years ago

(a) Look up the molar mass of Fe (= the atomic mass of Fe labeled "gFe/mol") (b) Divide16.7gFe by (a) to get moles of Fe (c) Multiply (b) by 2molFe2O3/4molFe (or 2/4) to get moles of Fe2O3 produced. (d) multiply (c) by the formula mass of Fe2O3* *To find...

17 years ago

1 mole of CaO = 40.08 + 16.00 = 56.08g/mol 1 mol Hg = 200.6 g/mol (a) Convert 36.0 gHg to moles: (36.0gHg)/200.6gHg/molHg = 0.1795 mol Hg (b) It takes 4 mol CaO to produce 4 moles Hg, so.... (0.1795 mol Hg)(4 mol CaO / 4 mol Hg) = 0.1795 mol CaO (c) Conve...

17 years ago

To find the number of moles, you divide the number of grams by the formula mass expressed in grams/mole: #moles = #grams / (formula mass)

17 years ago

The metal composition of the electrodes doesn't matter as far as generating H2 and O2 gases initially. However, it is desirable for the composition of the two electrodes to remain constant so that their performance will not change during electrolysis. Pla...

17 years ago

moles OH- = (liters)(molarity) (0.115 mol NaOH/L)(0.03383L) = 3.89x10-3 mol OH- used to reach the end point Moles acid = moles OH- moles of acid neutralized = 3.89x10-3 mol 0.288 g acid/0.03383L = 8.513g/L (8.513g/L)/(0.115 mol/L) = ________g/mole

17 years ago

C2H2 + O2 ---> CO2 + H2O (assuming complete oxidation) H-C---C-CH(CH3-CH3 + H2 ---> 3-methylbutene or 2-methylbutane, depending on the degree of hydrogenation (reduction) CH3CH2Cl + NaOH ---> NaCl + _____?

17 years ago

1. Since Zn is higher on the activity series than lead, the reaction would be: Zn(s) + Pb(NO3)2(aq) ---> ZnCl2(aq) + Pb(s) The zinc container would dissolve displacing Pb from the solution. Not a good choice of container. 2. Ag(s) + PbSO4(aq) ---> No reac...

17 years ago

Convert grams of phosphorus to moles of P4. Do likewise for grams of hydrogen, H2. To convert grams to moles you divide grams by the formula mass of that substance. The mole ratio of H2 reacting with P4 is 6/1. If the number of moles of H2 is 6 times (or...

17 years ago

When you have gases at the same temperature and pressure, the volume ratio is equal to the mole ratio. The ratio of the coefficients in the chemical equation can be used as mole ratios OR volume ratios: (11L CS2)(3 L O2 / 1 L CS2) = 33 L O2 *needed* Since...

17 years ago

Kinetic energy for a single molecule is Ek=(1/2)mv^2 [m = molecular mass, v = molecular velocity] The average of all the individual molecular kinetic energies is what you are asking for. The temperature of a substance is proportional to the average molecu...

17 years ago

The reaction is: Zn + 2HCl --> ZnCl2 + H2 1 mole of any gas at STP is 22.4 L 112L of H2 / 22.4 L/mol = 5 moles H2 (5 mol H2)(1 mol Zn / 1 mol H2) = 5 moles of Zn The above relationship assumes that the reaction is 100% efficient. Since the reaction is onl...

17 years ago

(a) Coefficients represent molecules, or formula units, or moles, depending on the situation. (b) Removing air from a sealed container reduces the pressure inside it. How this affects the container, depends on the strength and rigidity of the container. (...

17 years ago

What 2 to 1 ratio? The reaction is: P4+6H2-->4PH3. The limiting reagent is the reactant that you don't have enough of. Read my response to your question more carefully.

17 years ago

multiply the 5 moles of zinc by the factor: (1.00/0.85)

17 years ago

The procedure suggested by DrBob 222 will give the correct answer to the question. However, the wording of the question itself could be improved. It might be: "Calculate the total volume of solution (water + CaCl2) when a 0.0250 M CaCl2 s...

17 years ago

We would use a Friedel-Crafts alkylation of benzene: Benzene + 1-chloropropane ---> Propylbenzene + HCl. The catalyst used is AlCl3

17 years ago

One bromine atom becomes attached to the first carbon in the first stage of the reaction. The 2nd carbon becomes positive and bond with a water molecule which then loses a proton to form a hydroxyl group. H2C=CHCH2CH2CH3 + Br2 --> BrH2C-CH(+)CH2CH2CH3 + B...

17 years ago

2CO2(g) <=> 2CO(g)+ O2(g) Kp = 1 E-13 (or 1.00x10^-22) The LEFT side is favored. It is perfectly proper to write the reaction backwards: 2CO(g)+ O2(g) <=> 2CO2(g) BUT now the Kp is the reciprocal of 1.00x10^-22 or Kp = 1.00x10^22 for the rever...

17 years ago

Comment of my Qp calculation: I assumed that those percents are volume/volume percents. Since in the gas state moles are proportional to volume, and the partial pressure of each gas is proportional to moles, the volume percents were assumed to be proporti...

17 years ago

Let "omega" = w = angular velocity 1 rev/s = 2pi rad/s angular velocity = w = (0.400)(2pi rad/s) = 2.5133 rad/s Linear velocity = v = wr v = (2.5133 rad/s)(1.5m/rad) = 3.77 m/s Linear accel. = (change in velocity)/time = a a = (Vf - Vi)/t = (3.77 m/s - 0)...

17 years ago

Convert km/h to m/s: (90 km/h)(1000m/1km)(1 h/3600s) = 25.000 m/s (75 km/h)(1000m/1km)(1 h/3600s) = 20.833 m/s Let time of catching up = t The distance travelled by slower car = (20.833 m/s)(t) The distance travelled by faster car = (25.000 m/s)(t) The di...

17 years ago

1 Pa = 1 N/m^2 [I think you meant 105kPa = 105000Pa] (1.8)(105000Pa) = 189000 Pa = 189000 N/m^2 Total area of contact = (0.025 m2)(4) = 0.100 m^2 If you multiply the total pressure by the area of contact you will get the total weight in newtons. <b...

17 years ago

Coulomb's Law is: F = kQ1*Q2 / d^2 k is a constant Let's represent each charge as "q" then the intial force F1 is: F1 = k*q*q / 1^2 = kq^2 doubling the charge, the new force, F2, is: F2 = k(2q)(2q) / 1^2 = 4kq^2 F2 is how many times bigger t...

17 years ago

The combined resistance of resistors connected in series is the sum of their resistances. Just add the three resistances.

17 years ago

Go over the approximate solution solution I gave you in the previous question. You can improve the values you get by substituting and solving the quadratic equation, Ka = x^2 / c - x) The approximate solution is probably adequate. Check the method here: h...

17 years ago

For a pH = 4, [H+] = antilog(-4.000) = 1.00x10^-4 Ka = [H+][A-] / [HA] Let [H+] = [A-] = x Ka = x^2 / (c - x) , where c = molar concentration of HA before dissociation. if c is much larger than x, we can simplify the expression to: Ka = x^2 / c (1.00x10^-...

17 years ago

Use the Ideal Gas Law: PV = nRT Substitute: P = 0.973 atm V = Unknown. Solve for this variable. n = 0.01mol CO R = 0.0821 L.atm/K.mol [a constant] T = 9 + 273 = 282 K

17 years ago

Camphor has a carbonyl group which would produce an IR band at 1750 cm^-1. During the reduction, the C=O group would change to C-OH which absorbs IR at a much higher spatial frequency. The reduction might have been incomplete, with enough camphor present...

17 years ago

The equation is: 50 m = (1/2)(9.8m/s^2)(t^2) (It is less confusing to use absolute values here-No negative signs) t = sqrt[(2*50m)/(9.8m/s^2)] = sqrt(10.2s^2) (t = much shorter than 40.2 s)

17 years ago

Yours (Damon's) is a more elegant solution than mine, since you are using a more general formula for vertical motion and correct algebraic signs. I assume the relationship used is: Y = Yo + (1/2)gt^2, using the values you assigned. The zero point is the b...

17 years ago

Since the answer I got is a bit different from the one given, here is my complete take on this: Assume 1 mole of A and 1 mole of B reacting (This is legitimate since the yield should be independent of the actual number of moles used as long as they are eq...

17 years ago

I think the problem was constructed with the false assumption that the yield is independent of concentration and I accepted it uncritically. Le Chatelier's Principle still rules. Glad you were so alert. I checked [A]=[B]=3M with my setup and got a 75% yie...

17 years ago

100 km/h = 100000m/3600s = 27.8 m/s Vf^2 = Vi^2+2as The final velocity, Vf, is 0 0 = (27.8m/s)^2 + (2)(55m)(a) Solve for the acceleration, a. F = ma Use the acceleration from the previous step and the mass given to get the force, F.

17 years ago

The moles of each reactant are: (8.8g of Mg) / (24.3gMg/moleMg) = 0.362 moles Mg 21.0g N2 / 28.01 g/mol N2 = 0.750 mol N2 The mole ratio of Mg to N2 in the chemical equation is 3/1 The mole ratio in the mixture is 0.362 mol Mg / 0.750 mol N2 or 0.483 mol...

17 years ago

It is most likely cis,cis-1,4-dephenyl-1,3-butadiene. If you draw it you would see a U-shaped molecule with the two phenyl groups getting close together at the the ends of the "U". Formation of this isomer is probably prevented by crowding (steric hindran...

17 years ago

Another argument I just overlooked is that one of the reactants, cinnamaldehyde, contains a trans structure around the c=c double bond that is preserved in the final compound, 1,4-Diphenyl-1,3-butadiene. Thus, we cannot have two cis structures in the C=C-...

17 years ago

Metal + acid ---> metal salt + hydrogen gas Mg + HCl --> MgCl2 + H2 If you place the correct coefficient in front of HCl, you will have the chemical equation balanced for Cl and H (which it is not now).

17 years ago

The balanced chemical equation assumes a theoretical yield of 100%. To calculate the actual yield we must know the amounts of reactants (Mg and HCl) actually used.

17 years ago

I am giving outlines below for solving problems #1 and #2. The others involve the same or similar principles. The general topic is reaction stoichiometry. It is hard to cover such a broad topic adequately through postings here. Question #1 ...

17 years ago

The low pH is needed to prevent the Fe^+3(aq) indicator from hydrolyzing (forming hydroxy complexes and eventually iron(III) hydroxide). If the ferric salt indicator is altered, there is no clear end point during the titration.

17 years ago

Represent C #2 with a dot and C #3 with a concentric circle around the dot. C #2 (the dot) has two bonds coming out of it, one leading to a methyl, CH3 and another leading a Cl. C #3 (the circle) also has two bonds coming out of it, one leading to a methy...

17 years ago

Do a Google image search on "morphine isomers". Look at the best structure you can find. Locate the central carbon atoms that are linked to four different "groups". The four "groups" could be four carbon atoms which are linked to different parts of the mo...

17 years ago

Not sure if you are asking about a molecule or an ion. The only structure I could come up with that would obey the octet rule using 60 valence electrons was: Cl-O3-P-P-O3-Cl The two P's linked to each other. Each P attached to 3 O's. Each Cl linked to an...

17 years ago

Let the initial velocity = Vo The horizontal comonent, Vx = Vo(cos23) The horizontal distance, x = Vo(cos23)t = 8.7m t = 8.7m / Vo(cos23) The vertical component of initial velocity is Vyo: Vyo = Vo(sin23) Let the final vertical velocity be Vyf. Then, Vyf...

17 years ago

Do you need a numerical answer? If the bat is flying towards the wall, f' = f*[V+Vs) / V] f' = unknown, f = 35 kHz, V = 343 m/s (in dry air, 20 deg C), Vs = (5.0*2 = 10 m/s) <--Based on drwls</> suggestion, the source moves with a velocity of 5.0 m/s t...

17 years ago

I looked up two half reactions form a "Standard Reduction Potentials" table. The 2nd half reaction occurred in reverse as an oxidation. I doubled this reaction so that the number of electrons gained and lost are equal. Then I combined the two half reactio...

17 years ago

Convert 2.13 g TlOH to moles. Divide moles by 1 liter to get the molar concentration in moles/liter or "M". moles/L of TlOH = moles/L of OH- ions (since TlOH is a strong base). Calculate the pOH: pOH = -log[OH-] and pH = 14 - pOH

17 years ago

The concentration of SCN- in the first mixture is: (1/10)(0.0020M) = 0.0020M) The concentration of Fe+3 was: (9/10)(0.200M) = 0.18 M Since the concentration of F+3 was 90 times the concentration of SCN-, we may assume the equilibrium, Fe+3(aq) + SCN-(aq)...

17 years ago

A comprehensive look at this equilibrium system and the experiment for determining the equilibrium constant is given here: http://www.scienceteacherprogram.org/chemistry/Tehilla98.html

17 years ago

A condensed formula shows the functional groups in a molecule and any double or triple bonds, usually, on a single line. Here you have a a 4-carbon chain with a double bond between the 2nd and 3rd carbon. Also, methyl groups on carbons #2 and #3: CH3C(CH3...

17 years ago

Naming an organic compound or writing its name is not something you learn in one easy lesson. There are so many groups and so many rules. You need a course in organic chemistry just to get started. AP Chemistry and General Chemistry in college cover this...

17 years ago

A very similar question was posted and answered here: http://Jiskha.com/display.cgi?id=1218235719 Check it out for the method used. It is the same as your question. Only the numbers are slightly different.

17 years ago

*Convert 1.750g of Fe(NH4)2(SO4)2•6H2O to moles by dividing by the molar mass of this compound. *Find the moles of H2C2O4 using: moles = (liters)(mol/L) Te moles ratio of the two reagents id 1 to 1. That means that the smaller number of moles belon...

17 years ago

The topics of the questions you are asking are not covered adequately even in a college General Chemistry textbook. An Organic Chemistry textbook would be more helpful for most of the 13 questions. A good starting point for organic chemistry is the online...

17 years ago

1. Use: mass = (volume)*(density), or grams = (milliliters)(grams/ml) to calculate the mass (grams) of each compound. 2. Find the molar mass of toluene. 3. Divide the mass (grams) of toluene by the molar mass of toluene to convert grams to moles. 4. Conve...

17 years ago

To find the molarity, 1. Convert the 140 mLs of benzene to liters 2. Molarity = (moles of toluene) / (liters of benzene) NOTE: This is a continuation of the previous answer (finding the molality). Refer to steps 2 and 3.

17 years ago

Not sure what you mean by "atomic nature". The formula of glucose is C6H12O6 which shows you how many atoms of carbon, hydrogen, and oxygen there are in one molecule of glucose.

17 years ago

1. Find the the standard cell potential of the initial Al-Ni electrochemical cell (before the addition of NaOH). Consult your General Chemistry textbook on how to do this. 2. The solubility equilibrium is: Al(OH)3(s) <=>Al^3+(aq) + 3OH-(aq) Ksp = [Al+3][O...

17 years ago

The Rule of 5% may be reasonable but arbitrary. I have not seen it in any textbook I use. If the approximate solution is not satisfactory solve the quadratic equation: Ka = x^2 / (c-x) with he proper values for the Ka and c (the overall acid concentration...

17 years ago

If the plastic beads and the plastic beaker were electrically charged with the same kind of charge, how would they interact? I assume the beads are very light. When they were "poured" out of the beaker, What would the electrically charged beaker do to the...

17 years ago

1. HCl (strong acid completely split into ions) *Find the concentration after dilution using: V1M1 = V2M2 (8.00mL)(0.10 M) = (100.0 mL)(M2) *M2 = (8.00mL)(0.10 M) / (100 mL) = ?______M *pH = -log(M2) 2. HC2H3O2 (weak acid only partially dissociated into i...

17 years ago

I noticed I rewrote the Kp as 1x10^-22 instead of 1x10^-13. Sorry. In the comparison of Kp with Qp for the reverse reaction we have: Kp=10^13 > Qp=10^5, leading to the conclusion that CO is still changing to CO2 as it escapes and its concentration...

17 years ago

Set 1 varies from 1.374 to 1.400, a range of 0.026 Set 2 varies from 1.347 to 1.401, a range of 0.054 Set 3 varies from 1.301 to 1.499, a range of 0.198 The narrower (smaller) the range, the greater the precision. Now you should be able to rank the three...

17 years ago

GK

Questions

Answers