# Posts by Monique

Total # Posts: 325

**chemistry**

Balance the following redox reaction occurring in acidic solution. H+ + Cr --> H2 + Cr3+ H+ --> H2 do I add H+ to this side since H2 = 0? Also what about electrons. Cr -> Cr3+ + 3e- Hope I make sense

**chemistry**

Fe2+ + MnO-4 --> Fe3+ + Mn2+ Fe2+ = +2 Mn = +7 O-4 = 4(-2) = -8 Fe3+ = 3+ Mn2+ = 2+ ok so next I gave 8H to MnO-4 and 4 H20 to Mn2+ Next I starting adding my electrons. 1e- to Fe3+. I understand that. This is where Im lost according to my book I give 5e- to the reactant ...

**chemistry**

How does the N in NO2 have a oxidation state of 4+ please explain

**chemistry**

use oxidation states to identify the element that is being oxidized and the element that is being reduced in the redox reaction Sn + 4HNO3 ---> SnO2 + 4NO2 + 2H2O I see that SN is oxidized 0 --> 4+ and book says N is reduced +5 --> +4 I don't see that. Please help

**chemistry**

A rolaids tablet contains calcium carbonate which neutralizes stomach acid. If rolaids tablet neutralizes 42.15 mL of 0.320M hydrochloric acid, how many milligrams of calcium carbonate are in a Rolaids tablet CaCO3 + 2 HCl ------> CaCl2 + H2O + CO2 Pls show steps

**chemistry**

ok DrBob the answer i got was 2.7 x10-5 am i correct

**chemistry**

What is the concentration of the Mg2 ion in solution when [CO3-2] = 0.25M given that the Ksp= 6.82 x 10-6 for the following reaction MgCO3-------->Mg +. CO32- Chemistry - DrBob222, Friday, November 11, 2011 at 5:34pm Ksp = (Mg^2+)(CO3^2-) Substitute 0.25M for CO3^2- and ...

**Chemistry**

Name 3 buffers that exist in the human body? Include the conjugate and acid base pairs

**Chemistry**

For the reaction 2 N2O <===>O2 + 2 N2 what happens to the equilibrium position if the pressure is increased

**Chemistry**

Second thought I just don't understand what to do. pH= pKa + log [NH3]/[NH4NO3] pH= -l log ? + log (0.005/?) pH= ? pH= ?

**Chemistry**

Don't think I know how to calculate the M of NH4NO3

**Chemistry**

So is it a problem if the conch of NH4NO3 was not given to me. Or do I just assume it's the same as the NH3

**Chemistry**

Calculate the pH buffer made by combing 50.0 mL of 1.00M ammonia and 50.0mL of ammonium nitrate. Can I use the same formula? If so do I do anything with the mL

**chemistry**

DrBob I want to thank you SOOOOO much for all the help you give. I had never heard of the H H equation. And I also appreciate you patience

**chemistry**

This what I did log(1.76 x 10-5) +log(0.150/0.200) = 4.879

**chemistry**

No I'm sorry I just used this as the example of the H H equation

**chemistry**

pH = pKa + log ([A-]/[HA]) pH = pKa + log ([C2H3O2-] / [HC2H3O2]) pH = -log (1.8 x 10-5) + log (0.50 M / 0.20 M) pH = -log (1.8 x 10-5) + log (2.5) pH = 4.7 + 0.40 pH = 5.1 I used this example And I still got it wrong it should have been 4.75 + 0.12 = 4.87 or do I use just 4.7...

**chemistry**

Ok DrBob I think I got it after all the plugging in my final answer is 5.45 I hope

**chemistry**

calculate the pH of a buffer solution containing 0.200M acetic acid, HC2H3O2, plus 0.150M sodium acetate. The dissociation constant for HC2H3O2 is 1.76 x 10-5 I don't think our instructor gave enough notes on these things Im kind of winging it from the book. Could you ...

**chemistry**

I'm stuck Ka=1.84 x 10-4= x x/ 0.125 (1.84 x 10-4)[0.125] 2.3 x 10-5= x = [H30] lost which way do I go

**chemistry**

DrBob is the HCOOH---->H^++HCOO^ the HCHO2

**chemistry**

calculate the hydronium ion concentration in 0.125M formic acid, HCHO2 Ka= 1.8 x 10-4 can you show me the steps pls

**Chemistry**

What happens to the equilibrium constant when a catalyst is added to the reaction mixture. A. Increase B. Decrease C. Does not change D. Varies E. None of the above I chose c

**Chemistry**

What is the concentration of the Mg2 ion in solution when [CO3-2] = 0.25M given that the Ksp= 6.82 x 10-6 for the following reaction MgCO3-------->Mg +. CO32-

**Chemistry**

For the reaction Ag2S <====> 2Ag + S2 what happens to the equilibrium position if aqueous ammonium sulfide is added A. Shift left B. Shifts right C. Does nothing D. Doubles E. Halves

**Chemistry**

Identify the equation for which Keq= [Cu+]2[S2-]

**chemistry**

I got - log (0.0045) = 4.75

**chemistry**

what is the ph of a solution that has [H] = 0.0045 can you show steps pls

**chemistry**

I need help calculating [H3O] from pH and the pOH scale using my calculator. I have a TI-30XIIS

**chemistry**

what is the pH of a solution that has a H+ concentration equal to 1.76 x 10-5M? I got 4.75 is this correct

**chemistry**

what is the concentration of the hydroxide ion in an acidic solution?

**chemistry**

i think this is because water always has some ions in it. am i right

**chemistry**

If pure water cant conduct electricity why do we have to be careful with electrical appliances near water.

**chemistry**

a 25.0ml dsmplr og 0.105M HCI was titrated with 31.5ml of NaOH. What is the concentration of the NaOH I got 0.0834M am I correct HCI + NaOH -----> H20 + NaCl 25.0ml HCI x 1L/1000mlx0.105 mol HCI/1L HCI X 1 mol NaOH/ I mol HCI = 0.0834M

**chemistry**

A 13.03 g sample contains only ethylene glycol (C2H6O2) and propylene glycol (C3H8O2). When the sample is added to 100.0g of pure water, the resulting solution has a freezing point of -3.5C. What is the percent composition of ethylene glycol and propylene glycol in the ...

**corrected repost chemistry**

to what volume should you dilute 125mL of an 8.00M CuCl2 solution so that 50.0mL of the diluted solution contains 5.9g CuCl2 I have a hard time determing the M1V1=M2V2 is

**chemistry**

Describe how you would make 500.0mL of a 0.200M NaOH solution from a 15.0 stock NaOH conentration

**chemistry**

a 3.5L sample of a 5.8M NaCl solution is diluted to 55L.What is the molarity of the diluted solution

**chemistry**

Hydrochloric acid is usually purchased in concentrated form with a 37.0% HCL concentration by mass and a density of 1.20g/mL. How much of the concentrated stock solution in milliliters should you use to make 2.5L of 0.500M HCL

**chemistry**

how much of a 1.50M solution sodium sulfate solution in milliliters is required to completely precipitate all the barium in 150.0mL of a 0.250 M barium nitrate solution

**chemistry**

A 45.8mL sample of 5.8M KNO3 solution is diluted to 1.00L. What volume of the diluted solution contains 15.0 g of KNO3.

**chemistry**

A KNO3 solution is made using 88.4g of KNO3 and diluting to a total soultion volume of 1.50l. Calculate the molarity and mass percent of the solution. Assume a density of 1.05 g/mL for the solution.

**chemistry**

an aqueous solution containing 17.5g of an unknown molecular(nonelectrolyte) compound in 100.0g of water has a freezing point of 1.8 degress C. calculate the molar mass of the unknown compound

**chemistry**

An ethylene glycol solution is mad using 58.5g of (C2H6O2) and diluting to a total volume of 500.0 mL. Calculate the freezing and boiling point. Assume a density of 1.09 g/ml for the solution

**chemistry**

A glucose solution contains 55.8g of glucose (C6H12O6) in 455g of water. Calculate the freezing poing and boiling point of the solution. (Assume a density of 1.00 g/ml for water. This what I did, I got moles of C6H12O6, 0.89 moles C6H12O6 then I got the mass of the solution ...

**chemistry**

DrBob222 I think Im doing something wrong. When I worked this problem out I came up with the right answer but wrong units. 0.112L KOH x 0.100molKOH/LKOH x 1mol H3PO4/3 mol KOH x 0.01 L H3PO4/1 mol H3PO4 = 0.373 L H3PO4

**chemistry**

a 10.0mL sample of an unknown H3PO4 solution requirs 112mL of 0.100 M KOH to completely react with the H3PO4. What was the concentrartion of the unknown H3PO4 solution? H3PO4 + 3KOH -----> 3H2O + K3PO4 Ive seen these problems with one volume but not two volumes Im lost ...

**chemistry**

where did you get the 96.2

**chemistry**

If im given mass percent and mass solvent how do I find mass solute and mass solution. example: Mass percent = 3.8% and Mass solvent 45.8 g. Find mass solute and mass solution

**Statistics**

The distribution of heights of adult males has a mean of 69 inches and a standard deviation of 4 inches. A random sample of 36 adult males is selected. Find the probability that the average height will be more than 70 inches. a.0.668 b.0.858 c.0.908 d.0.995

**statistics**

Suppose a random sample of 25 students is selected from a community college where the scores in the final exam (out of 125 points) are normally distributed, with mean equal to 112 and standard deviation equal to 12. Find the probability that the sample mean deviates from the ...

**chemistry**

an 8.5g ice cube is placed into 255g of water. Calculate the temp change in the water upon the complete melting of the ice. Hint: Determine how much heat is absorbed by the melting ice and then use q = mc^T to calculate the temp change of the 255g of water

**Chemistry**

A mixture containing 235 mg of Helium and 325 mg of neon has a total pressure of 453 torr. What is the partial pressure of Helium

**Chemistry**

Consider the chemical reaction C + H2O -----> CO + H2 How many liters of hydrogen gas are formed From the complete reaction of 1.07 mol of C? Assume that the hydrogen gas is collected at a pressure of 1.0 atm and the temperature of 315K So I'm looking for volume and I ...

**Chemistry**

Ahhhhh thank you!!!!! I was so frustrated

**Chemistry**

How many moles of gas must be forced into a 3.5 L ball to give it a gauge pressure of 9.4 psi at 25 degrees C? The gauge pressure is relative to atmospheric pressure. Assume that atmospheric pressure is 14.7 psi so that the total pressure in the ball is 24.1 psi Ok so I'm ...

**Chemistry**

In this reaction, 4.58 L of O2 were formed at 745mm Hg and 308 K. How many grams of Ag2O decomposed. 2 Ag2O----> 4 Ag + O2 Please help I'm very confused

**Chemistry**

A chemical reaction occurring in a cylinder equipped with a movable piston produces 0.58 mol of a gaseous product. If the cylinder contained 0.11 mol of gas before the reaction and had an initial volume of 2.1 L, what was it's volume after the reaction. Am I doing this ...

**Chemistry**

A snorkeler takes a syringe filled with 16 mL of air from the surface, where the pressure is 1.0 ATM, to an unknown depth. The volume of the air in the syringe at this depth is 7.5 mL. What Is the pressure at this depth? If the pressure increases by an additional 1 atm for ...

**Chemistry**

Convert a pressure of 23.8 in. Hg into kilopascal. Ok so I looked up kilopascal and it Said 1 Kpa = 1000 pa So I began to set it up like this 23.8 / 29.2 x1000 am I correct Chemistry - DrBob222, Thursday, October 13, 2011 at 1:48pm I don't think that will get it. I would ...

**Chemistry**

DrBob222 I used 29.2 in Hg because my book gave me 1 atm = 29.92 in. Hg. But why did you use 1atm/760mm

**Chemistry**

Convert a pressure of 23.8 in. Hg into kilopascal. Ok so I looked up kilopascal and it Said 1 Kpa = 1000 pa So I began to set it up like this 23.8 / 29.2 x1000 am I correct

**Chemistry**

Convert a pressure of 23.8 in. Hg into kilopascal. Ok so I looked up kilopascal and it Said 1 Kpa = 1000 pa So I began to set it up like this 23.8 / 29.2 x1000 am I correct

**chemistry**

How many moles of O2 are needed to form 3 moles of Al2O3 from the element

**Chemistry**

A thief uses a bag of sand to replace a gold statue that sits on a weight sensitive alarmed pedestal. The bag of sand and the statue have exactly the same volume 1.75 L. Assume that the mass of the bag is negligible. A) calculate the mass. ( density of gold = 19.3 g/cm3

**Stoichiometry**

I think I got it 6 mol A / 2 mol A x3 mol B = 9 mol B

**Stoichiometry**

So I have this question it reads Consider the generic chemical reaction How many moles of B are required to completely react with 2A + 3B ==> 3C 1. 6 mol of A 2. 2 mol of A I won't put them all just guide me in the right direction please

**Stoichiometry**

Consider the reaction between reactants S & O2 2S(s) + 3 O2(g) ==> 2 SO3(g) If a reactant vessel initially contains 5 mol S and 9 mol O2, how many moles of S, O2 and SO3 will be in the reaction vessel once the reactants have reached as much as possible? Assume 100% actual ...

**Stoichiometry**

Consider the reaction between reactants S & O2 2S(s) + 3 O2(g) ==> 2 SO3(g) If a reactant vessel initially contains 5 mol S and 9 mol O2, how many moles of S, O2 and SO3 will be in the reaction vessel once the reactants have reached as much as possible? Assume 100% actual ...

**Stoichiometry**

Find the limiting reactant for the initial quantities of reactants 2k(s) + Cl2(g)--> 2KCl(s) 1.8 mol K; 1 mol Cl2 I'm lost

**Stoichiometry**

Find the limiting reactant for the initial quantities of reactants 2k(s) + Cl2(g)--> 2KCl(s) 1.8 mol K; 1 mol Cl2 I'm lost

**Stoichiometry**

For each precipitation reaction, calculate how many grams of the first reactant are necessary to completely react with 17.3 g of the second reactant. 2KI(aq) + Pb(NO3)2(aq)--->PbI2(s) + 2KNO3(aq) Not looking for the answer I really want to know if I did it correctly 17.3g ...

**Chemistry**

Is it true that Na+ and K+ are always spectator ions in reactions that involve sodium and potassium compounds

**Chemistry**

What does it mean by aq excess and is this something I need to pay attention to. Does it help me balance the equation

**Chemistry**

I need help balancing this problem HClO3(aq excess) + CaCO3 I got to HCO3 + CaCiO3

**Chemistry**

Calculate the number of moles in 22.6 g C3H7OH 22.6g C3H7OH x 1 moL C3H7OH /60.11g C3H7OH = 0.375 molC3H7OH Am I right

**Chemistry**

What is the mass of 0.0065 mole of ruthenium 6.5 mol Ru x101.07g Ru/1mol Ru = 0.656g Ru Or is it 0.66g Ru

**Chemistry**

Li(s) + N2 6Li(s) + N2 ==> 2 Li3N Li =6. Li =6 N= 2. N =2 Am I correct now

**Chemistry**

Li(s) + N2 6Li(s) + N2 ==> 2 Li3N Li =6. Li =6 N= 2. N =2

**Chemistry**

I have to put the correct complete and balanced equation for Li(s) + N2(g) Li(s) +N2(g) --- LiNi2(s) I think I'm correct what do you think

**Chemistry**

What is the net ionic equation for the reaction Cu(s) + 2 Ag (NO3)2(aq) --- Cu(NO3)2(aq) + 2AG(s)

**Chemistry**

C4H10O(l) + O2(g) --- CO(g) + H2O(g) When I balanced it I got this C4H10O(I) + 4O2(g) --- 4CO(g) + 5H2O Am I correct

**Chemistry CONFUSED**

I don't want the answer. Do I have to account for the molar mass of CO2 and O2.

**Chemistry CONFUSED**

Ok I'm really confused on the question I asked how many CO2 molecules can be made with 0.500 mol of oxygen atoms. Please help with setting this up

**Math**

got it. Thanks so much.

**Math**

is that with the requirement that each couple sit side by side?

**Math**

Four couples have purchased ticket to the school play. Their sear are next to one another in a single row. If each couple sits side by side, how many seating arrangements are possible? (I came up with 24. correct??)

**Chemistry**

When the following equation is balanced with the smallest integral coefficients, the coefficient of the HNO3 is Li2CO3(s) +HNO3(aq) -- LiNO3(aq)+H2O(l)+CO2

**Chemistry HELP**

Calculate the number of molecules in 3.11 mol of CCL4 I got 2.88E26 am I correct

**Chemistry**

I don't understand how to work this problem can you help

**Chemistry**

How many CO2 molecules can be made with 0.500 mol of oxygen atoms?

**Chemistry**

Calculate the number of molecules in 3.11mol of CCL4 this is what I'm doing I got the molecular weight of CCL4 which is 181.88 Then I set it up like this 3.11 mol CCL4/ 181.88 mol CCL4 x 6.022E23 = 1.03E22 Am I right

**Chemistry**

I did Zn(2)=65.39 then I divided that by the amu of Zn(NO3)2 x 100 is that right

**Chemistry**

What is the percent zinc in Zn(NO)3 2xZn/189.41]=34.52% am I right

**Chemistry**

What is the formula mass for (NH4)3PO4

**Math**

why adding 1=I Rather then 1-i

**Chemistry Please Help**

So this is what I did 1E6kg x 1 mole Fe/55.85g= 17905 moles Fe 17905 mole Fe x 1 mol Fe2o3/2mol Fe *159.70g/1moleFe2O3* 1kg/1000= 1429kg

**Chemistry Please Help**

Iron is found in Earths crust as several different iron compounds. Calculate the mass (in kg) of each compound that contains 1.0 x 10E3 kg of iron. Fe2O3 Please help step by step

**Chemistry**

I got that as well but then I took the molar mass and divided by the empirical formula and got C8H10N4O2

**Chemistry**

Caffeine a stimulant found in coffee has the mass composition of C, 49.48%, H, 5.19%, N, 28.85%, O 16.48%. The molar mass of caffeine is 194.19g/mol. Find the molecular formula for caffeine.