Tuesday

September 23, 2014

September 23, 2014

Total # Posts: 285

**Math**

The number p is the product of three different positive prime numbers greater than 2.If the sum of these three prime number is also prime, what is the smallest possible value for p? Won't the 3 number be 3-5-11? Thanks
*May 21, 2014*

**chem**

that just confused me ....so i used q2 and then q4....because going from a ice to stream is another conversion
*April 23, 2014*

**chem**

Calculate the amount of heat required to convert 17.5g of ice at -33.5∘C to steam at 100.0∘C.
*April 23, 2014*

**math**

a car travel 60 km 18 minutes.at the same average speed,how far will it travel in 1hour 12minutes
*January 21, 2014*

**Calculus**

Find the position s as a function of time t from the given velocity v=ds/dv. Then evaluate the constant of integration so that s = s0 when, t = 0. 1. v = 3t2 , s0 = 4 I don't quite understand what the question is asking or what is s0 mean. Than
*January 12, 2014*

**Physic**

A horizontal force F pulls a mass m across the floor at constant speed a distance d. If the coefficient of friction between box and floor is u, the work done by the force F is. I know W= FD and Wf = umgd, but I don't understand what the question asking. Thanks
*December 8, 2013*

**chemistry**

In the following reaction, how many liters of carbon dioxide, CO2, measured at STP, would be produced from the decomposition of 143 g of magnesium carbonate, MgCO3? MgCO3----MgO+CO2
*November 19, 2013*

**chemistry**

sorry but i just got soo confused
*November 19, 2013*

**chemistry**

Hydrogen gas can produced by the reaction between metallic aluminum and aqueous hydrochloric acid 2Al+6HCl----2AlCl3+3H2 Hydrogen gas produced by this reaction is typically collected via water displacement, during which time the hydrogen gas becomes saturated with water vapor...
*November 19, 2013*

**Physic**

An elevator weighing 2000 kg falls with a downward acceleration of magnitude (1/2)g . What is the tension in the supporting cable? I got the answer as 49000 N.
*September 16, 2013*

**Physic**

A car traveling 100 km/h is 200m away from a truck traveling 50 km/h (in the same direction). Assuming constant braking acceleration, what is the minimum deceleration the car must have if it is not to hit the truck? Can someone hint me on how I can start this problem? Thanks
*August 28, 2013*

**Math**

Let say 5m x 5m, I know the answer is 25 m^2, but let say it was 25m / 5m, what would the answer be? I know it 5 but what the unit? Just 5m? Thanks
*August 25, 2013*

**Significant Figures**

Well, it have no decimal places so I don't know how many significant figure should the answer be
*August 22, 2013*

**Significant Figures**

The problem is 150 - 1 - 0.182 Since the least sig. fig. is 1 would the answer be 1 x 10^3 ?Thanks
*August 22, 2013*

**Math**

The problem I have to solve is log with base 2 ^6 multiply by log base 6 ^ 8. I use the change of base formula and got log6/log2 * log8/log6 Which become log6/log2 * log2()^3/ log 6 I'm stuck here thanks.
*June 18, 2013*

**Chemistry**

So I did a lab that consist of baking cookies and the mass of the final products isn't equal to the ingredients used. Could there be mass lost as gas ? What other factors might there be? Thanks
*May 26, 2013*

**Chemistry**

Find the polar coordinate of the following. (0,-6) I know r = sq.root of 6 but tan theta = -6/0 doesn't exist so how will I find the degree? Thanks
*May 19, 2013*

**Chemistry**

Find the enthalpy for : 4Fe + 3O2 = 2Fe2O3 I got the following informations: Fe + 3H2O = Fe(OH)3 + 3/2H2 - Enthalpy is 160.9 kj H2 + 1/2O2 = H2O - Enthalpy is -285.8 kj Fe2O3 + 3H2O = 2Fe(OH)3 - Enthalpy is 288.6 I try using Hess Law but cannot solve it. Can anyone help me ...
*May 13, 2013*

**Chemistry**

3-Pentene **
*May 9, 2013*

**Chemistry**

Name the compounds CH3CH2CHCH2CH3 - Is this 3-Pentane? Thanks
*May 9, 2013*

**Chemistry**

How much water must be added to 6 mL of a 0.05M stock solution to diltue it to 0.02M ? The answerI got is 15 mL. Is this correct? Thanks
*April 18, 2013*

**Math**

Is 2Cos x the same thing as Cos^2 x? Thanks
*April 7, 2013*

**Precalculus**

Verify the identities. Cos^2x - sin^2x = 2cos^2x - 1 When verifying identities, can I work on both side? Ex. 1 - sin^2x - sin^2x = 1 - 2sin^2x 1 - 2sin^2x = 1 - 2sin^2x
*April 3, 2013*

**Chemistry**

Now that you mention it, I checked and under those conditions , the first value should not be 3.21 mols. So I guess that why I was unable to get the correct answer for 5.29 mols.I think the point of the conditions was just to say that the condition for the change were the same...
*April 1, 2013*

**Chemistry**

If 3.21 mol of a gas occupies 56.2 L at 44*C and 793 torr, 5.29 mol of this gas occupies __________ L under these conditions. . -How will I solve this using PV= nRT? I tried using PV= nRT. By just plugging in the value and got 131 but the answer is around 92.6. Thanks
*April 1, 2013*

**Chemistry**

Does mass affect pressure? I understand volume, and temperature does but not sure about mass. If I have a gas with mass 15 g, wont this exert less pressure than a gas have a mass of 30 g?
*April 1, 2013*

**Chemistry**

Calculate the grams of oxygen gas present in 2.5 L sample kept at 1.66 atm pressure and a temperature of 10 C. - I got 5.72 grams Determine the volume of oxygen gas needed to completely combust 0.202 L of Butane(C4H10). -I got 1.31 L O2. -Thanks
*March 31, 2013*

**Chemistry**

Bob, could you verify this answer for me too please? Thanks P1 = 1.08 atm V1 = 250 mL T1 = 297 K T2 = 310.2 K P2 = 2.25 atm Would V2 = 125.3 mL?
*March 31, 2013*

**Chemistry**

For Boyle, Lussac, and Charles Law, do I have to convert the units to the standard measurement? Like temperature to kelvin and pressure to atm? Thanks
*March 31, 2013*

**Chemistry**

The temperature of oxygen is 810 torr at 298 K , what will the pressure be at 330 K? Using Lussac's Law, would the answer be 896.98 torr? Thanks
*March 31, 2013*

**Chemistry**

Thanks you for the balanced equation!
*March 29, 2013*

**Chemistry**

So CH4 + O2 = CH3OH ?
*March 29, 2013*

**Chemistry**

What do you mean there are procedures? Thanks
*March 29, 2013*

**Chemistry**

Determine the volume of methane CH4 gas needed to react completely with 0.660 L of 02 to form methanol CH3OH I'm confused because I'm sure CH4 + O2 don't give you CH3OH. Thanks
*March 29, 2013*

**Chemistry**

Do elements with higher masses always have lower average velocity than those elements with a low mass? Thanks
*March 12, 2013*

**Chemistry**

I thought KE is joules and not celcius so I'm confuse.
*March 11, 2013*

**Chemistry**

The question is What is the root mean square velocity of ammonia molecules (NH3) at 45°C? -My teacher is telling me to use the formula KE=1/2MV^2 to find the velocity and told me to use 45 celcius as the KE and molar mass as M and solve for V^2. (45=17 * V2)
*March 11, 2013*

**Chemistry**

I had to find the root mean square velocity of a gas using the only formula KE=1/2MV^2 . Is this even possible using only this formula?
*March 11, 2013*

**Chemistry**

I had to find the root mean square velocity of a gas using the only formula KE=1/2MV^2 . Is this even possible using only this formula?
*March 11, 2013*

**Chemistry**

Water has an extremely high boiling point compared to other compounds of similar molar mass because of ? Hydrogen Bond Adhesive force Covalent bonding Dispersion Forces I believe the answer is A since hydrogen bond is a strong bond and thus require most energy to break them. ...
*March 10, 2013*

**Precaculus**

Would the answer be =1 since tan4.7* cot 4.7 = 1? Thanks
*March 6, 2013*

**Precaculus**

tan4.7 * cot4.7 I understand tan4.7 = 1/ cot 4.7 but I'm stuck after this thanks.
*March 6, 2013*

**Chemistry**

Quotes from wiki "Adhesion is the tendency of dissimilar particles or surfaces to cling to one another" So I'm thinking it is an attractive force? Thanks
*March 5, 2013*

**Chemistry**

What are the attractive forces that increase surface tension? -Would it be cohension and adhension? Thanks
*March 5, 2013*

**Math**

I'm being asked to solve f(4) = f(4-1) + f(4-2). The answers is 3, but I don't know how to get to that answer. Thanks
*March 2, 2013*

**Math**

n = 4
*March 2, 2013*

**Math**

How would I solve this part of the Fibonacci sequence piecewise function? f(n) = f(n-1)+f(n-2) if n > 1. Thanks
*March 2, 2013*

**Chemistry**

4Fe + 3O2 = 2Fe2O3 So in math book it say " You can interpret this equation in terms of representative particles by saying that four atoms of iron react with three molecules of oxygen to produce two formula unit of iron(iii) oxide" Why it say that there are 4 atoms ...
*February 24, 2013*

**Chemistry**

I need to write a balance equation of the decomposition of aluminum carbonate. I know the starting "reactant" is Al2(CO3)3 but would the "product' be 2Al + 3(CO3) ? Thanks
*February 18, 2013*

**English**

Is there a present and past tense of "is" and "are" ? Or it is just how they're used in the sentence that make them past/present tense? Thanks
*February 18, 2013*

**Chemistry**

If I have 50 mL of Lead(II) Nitrate, it is possible for me to calculate how many mole is 1 mL of the substance? Thanks
*February 17, 2013*

**Chemistry**

Because the mass of the reactants equal to the mass of the product of a reaction, the number of moles will be conserved. -I think this is sometime true but I don't know a way to prove that it sometime true. Anyone got an idea ? Thanks
*February 10, 2013*

**Math**

Oh, thanks you so much! I did not realize f(x-3) and (x-3) make such different.
*February 9, 2013*

**Math**

Let say the other function is x-2 , if x < 0 x^2 + 1 , if x >= 0 f(-4) would be -6? I kind of not understand why do we keep going down the value. Thanks
*February 9, 2013*

**Math**

I believed the answer is 16 but computer teacher is telling me it 1. Thanks
*February 9, 2013*

**Math**

Solve the piece wise function when f(17) f(x) = f(x-3)+2 if x > 10 -5 if x <= 10 Would the answer be 1? Thanks
*February 9, 2013*

**Chemistry**

A mole of a pure substance contains 6.02x10^23 atoms. Alway true, sometime true or never true? -I was thinking sometime true since a pure substance can be like H2O but H2O have 3 "atoms" (Is this what you call individual part of H2O?). Each "atoms" have 6....
*February 5, 2013*

**Chemistry**

Since there is 5H2O is about 36% of CUSO4 + 5H2O , would there be about 16 g of residue left over? Thanks
*February 3, 2013*

**Chemistry**

If 25 grams of copper(II) sulfate pentahydrate were heated until all water was removed, how much residue would remain?- Could someone help me understand this question? I don't understand it at all. Thanks
*February 3, 2013*

**Chemistry**

Dr.Bob, do you think there is a formula for animals fats? I can only find the different formula for different lipids. Thanks
*February 3, 2013*

**Chemistry**

Is there a chemical formula for animal fats? - Would the lipids chemical formula be the same as animal fats? Thanks
*February 3, 2013*

**Chemistry**

DrBob, let say the mass of H2O is 18 g. Would 1 gram of water be about 0.05 mole of H2O? Thanks
*February 3, 2013*

**Chemistry**

I did a lab that involve cooking meat and finding the mass of lipids, meat tissue and water. For a chicken sample the original mass was 20 gram. After cooking there was 15.5g of meat, and 1.5 g of oil, and 1 g of water. I am missing 2 g of the original mass. Anyone have any ...
*February 3, 2013*

**Chemistry**

Thank you so much for that explanation!
*January 29, 2013*

**Chemistry**

The problem ask what is the mass of iron(iii) chloride contains 2.35 x 10^23 chloride ions. I understand the molar mass is 162.20 g/mol. - 2.35 x 10^23 chloride ions would be around 0.39 moles. - The work that my teacher gave me is 0.39 moles * (1 mol FeCl3 / 3 mol chloride ...
*January 29, 2013*

**Chemistry**

It would be 0.00023 mol .Thank you. Let say if they want to know the amount of ions. I would just have to multiply that number by avogadro number right? Thanks
*January 29, 2013*

**Chemistry**

I mean Ag but not NO3 **
*January 29, 2013*

**Chemistry**

Since the AgNO3 have a molar mass of 169.87 g. I divided that by 0.02 g and got 0.000118 moles of AgNO3. How would I find how many moles is Ag and how many is NO3? Thanks
*January 29, 2013*

**Chemistry**

How many moles of ion are in the following? A. 0.0200 g AgNO3 - Could someone give me the step to solve such problems? Thanks
*January 29, 2013*

**Chemistry**

Is this true or false? Thanks A mole of CCl4 is composed of one atom of carbon and four atoms of chlorine. I put false because it contain one mole of C 4 mole of Cl. Each mole have more than one atoms. Thanks
*January 29, 2013*

**CHM**

There is 8. NH4 is ammonium. There is 4 hydrogen in each ammonium so 2 ammonium would give you a total of 8 hydrogen.
*January 27, 2013*

**Chemistry**

Oh. Typo sorry. So CuSO4 + NAOH would be Cu(OH)2 + NA2SO4? Thanks
*January 27, 2013*

**Chemistry**

Let say Pb(NO3)2 combine with FeCl3, would this yield PbCl + Fe(NO2)3? Thanks
*January 27, 2013*

**Language Art**

I'm currently doing a project and need a physical object to represent "racism". Anyone have a suggestion of such item? Thanks
*January 25, 2013*

**Math**

If it was 1040 gallons it would be around 9.1 tons right? Thanks Ken
*January 22, 2013*

**Math**

The metric ton of CO2 product per gallons of gas can be calculated with the following. 8.78 x 10-3 metric tons of CO2 are emitted per gallon of gas. Let say the gallon of gas is 1288. Would the CO2 produced be around 11.3 tons? Thanks
*January 22, 2013*

**Chemistry**

Let say you were given this equation: NiBr2 + Co = Ni + CoBr2 How can you tell which is liquid,gas,solid,aqueous? Do you just use what you know and figure it out? Like since NiBr2 can be broken down because of the solubility rule, you can assume it aq then Co is a metal so you...
*January 13, 2013*

**Chemistry**

The world equation didn't have any sulfate on the product side :(. I'm guessing such formula can't be right since how can there be sulfate on one side and there none on the other. So the words equation is wrong right? Thanks
*January 13, 2013*

**Chemistry**

I need to write the total ionic equation for this equation. Copper(ii)sulfate + iron = iron(iii)+ copper. Won't it be Cu2+ + SO4-2 + Fe = Fe3+ + Cu ? The answer key say 3Cu2+ + 3SO4-2 + 2Fe = 2Fe3+ + 3SO4-2 + 3Cu Where did they get the sulfate for the product from? Didn&#...
*January 13, 2013*

**Chemistry**

Oh, thanks you for that! If it was H2O2 + O2 + Heat = H2O + O2 it would still be decomposition?
*January 13, 2013*

**Chemistry**

DrBob, could you clarify what you mean by " one compound on the left forms more than one on the right" Thanks.
*January 13, 2013*

**Chemistry**

H2O2 + Heat = H2O + O2 Would this be combustion or decomposition? Since the products are H2O and O2, I thought it would be combustion but then H2O can be decompose into H2O and O2 which would be decomposition.
*January 13, 2013*

**Science**

Could anyone link or tell me why does oxygen ignite at high temperature? Thanks
*January 13, 2013*

**Sicnece**

A skeleton equation is not a balanced equation.- Is this sometime true, never true or always true? Can't there be some skeleton equation that is already balanced, thus it sometime true? Thanks
*January 8, 2013*

**Chemistry**

I mean OH sorry. So this isn't one of the 6 type of reactions? Thanks
*December 18, 2012*

**Chemistry**

Would this be a double or single replacement and why? Thanks Na2O2 + H2O -> NaOH + O2 Would it be single since the Na is pair with H?
*December 18, 2012*

**English**

I'm not a native speaker of English so I have grammar problems. What are some ways that I can improve my grammar? Do reading grammar book help? Also, is there any way to improve my writing beside writing more? Thank you
*December 17, 2012*

**Chem:DrBob**

When you write the formula in word equation would it be : Octasilicon and oxygen reacted to produce sulfur trioxide? Would this be the balance equation? S8 + 12O2 -> 8SO3
*December 17, 2012*

**Chem:DrBob**

So since it S3O6, it was reduce to SO3?
*December 17, 2012*

**Chem:DrBob**

Thank you for the informative answer yesterday. I hope you can help me with this one too. Thanks S(subscript 8) + O( subscript 2) -> SO3 Could you explain why it O3 when S valence is -2? Thanks
*December 17, 2012*

**Chemistry**

I'm currently learning about balancing chemical equation but I don't understand the equation below. 2FE + 3CL(subscript 2) -> 2FECL(subscript 3) I understand 2FE balance out but how did 3CL2 became CL3? Thanks
*December 16, 2012*

**Chemistry**

Find the energy( in KJ) of a wave with the wavelength of 507 nm. First, I turn the 507 nm into meter then divide the speed of light by it which give me the frequency. Then I take the frequency and multiply by the planck. Then I would convert the Joule to KiloJoule.- Would this...
*November 7, 2012*

**Chem:DrBob**

Dr.Bob, yesterday you told me : "The best way I think is to show examples. 12Mg = 1s2 2s2 2p6 3s2 Here the 1s orbital is lower than the 2s and they are lower than the 3s etc." 19K = 1s2 2s2 2p6 3s2 3p6 3d0 4s2 Here the 1s is lower than the 2s and those are lower than...
*November 6, 2012*

**math**

A number plus sixteen.
*November 6, 2012*

**algebra 2**

The answer would be (2x+3)(x+1). Do you need an explanation on how to do such problem?
*November 6, 2012*

**Chemistry**

Is this always true, sometime true, or never true? The orbitals of a principal energy level are lower in energy than the orbitals in the next higher principal energy level. -I'm thinking sometime true but I can't figure out how to explain why it sometime true. Thanks
*November 6, 2012*

**Math**

Is there a way to simplify this further? Thanks (√ x + √ y) / x^2+y^2 ( Square root of x plus square root of y) All divided by x^2+y^2.
*September 20, 2012*

**Chemistry**

Could someone give me the steps to converting using the metric system scientific notation? For example, how would I convert 2.2 x 10^2 cm to km? Thanks ( I try Google but they only teach how to convert it when it not in scientific notations form)
*September 18, 2012*

**Chemistry**

Could someone tell me how to use SI prefixes to convert within the SI unit system or link me to a website that teaches this? Thanks
*September 18, 2012*

**Math**

Rounds each number to four significant figures. ( Could someone check if I'm right? Thanks) a. 431801 = 4318 b. 10235.0 = 1024 c. 1.0348 = 1.035 d. 0.0004384010 = 0.0004384 e. 0.00078100 = 0.0007810 f. 0.0098641 = 0.009864
*September 11, 2012*