A photoelectric experiment is performed by separately shining a laser of 450 nm (blue light) and 560 nm (yellow light) on a metal surface and measuring the number and kinetic energy of the ejected electrons. The threshold frequency of the metal is 6.0010^14 Hz. a. ...
Wednesday, April 15, 2015 at 2:48am
In an alternate universe, electron energies in an atom are found to obey the following equation where n is the principle quantum number: E = 3.0 x 10^(-19) J * nm * (1/n^2) ..where n is the principle quantum number A gas discharge lamp, like the lamps used in lab, contains ...
Wednesday, April 15, 2015 at 12:56am
Elin estimates her probability of passing French 0.6, passing chemistry is 0.8, (a)determine the probability that elin will pass French but fail chemistry (b) pass chemistry but fail French (c) pass both classes (d)fail both classes
Wednesday, April 15, 2015 at 12:23am
Suppose that 18.84 mL of 0.315 M Ca(OH)2 is required to neutralize 18.2 mL of aqueous HCl solution. What is the molarity of the HCl solution? All help is appreciated. Would also like help showing which numbers go where within any equations! Thanks so much!
Wednesday, April 15, 2015 at 12:00am
Determine the hydronium ion concentration in a solution that is 0.00027 M HCl. Answer in units of M. Determine the hydroxide ion concentration in a solution that is 0.00027 M HCl. Answer in units of M. This is a two part question and I have tried multiple times and every time ...
Tuesday, April 14, 2015 at 11:32pm
For the neutralization reaction involving HNO3 and Ca(OH)2, how many liters of 1.55 M HNO3 are needed to react with 45.8 mL of a 4.66 M Ca(OH)2 solution? 1. 0.137 L 2. 0.0343 L 3. 0.275 L 4. 1.32 L 5. 0.662 L 6. 0.330 L
Tuesday, April 14, 2015 at 11:11pm
Chemistry: Potentiometric Anyalysis
If the pH probe was miscalibrated and reports the pH to be 1 unit higher than the true pH of the solution it is in, would the molar mass you report for the solid acid be higher, lower, or equal to the true molar mass of the acid? This for my post lab write up. I think that the...
Tuesday, April 14, 2015 at 10:32pm
A chemist dissolves 0.097 g of CuSO4 · 5 H2O in water and dilutes the solution to the mark in a 500-mL volumetric flask. A 13.6-mL sample of this solution is then transferred to a second 500-mL volumetric flask and diluted. What is the molarity of CuSO4 in the second ...
Tuesday, April 14, 2015 at 9:58pm
1.How many grams of KCl is in 225 mL of a 0.452 M solution? 2.What volume in mL of 0.555 M solution contains 85.0g Na2SO4? 3.How many grams of CaCl2 would be dissolved in 2.0L of a 0.10 M solution of CaCl2? Can you please show me how to do these problems?
Tuesday, April 14, 2015 at 9:52pm
carbon dioxide (CO2) gas is produced as a result of the reaction between calcium carbonate and hydrochloric acid. The gas that is produced is collected in a 20 dm3 container. The pressure of the gas is 105 kPa at a temperature of 20 C. What mass of carbon dioxide was produced?
Tuesday, April 14, 2015 at 8:14pm
A solid weak acid is weighed, dissolved in water and diluted to exactly 50.00 ml. 25.00 ml of the solution is taken out and is titrated to a neutral endpoint with 0.10 M NaOH. The titrated portion is then mixed with the remaining untitrated portion and the pH of the mixture is...
Tuesday, April 14, 2015 at 7:24pm
The heat of fusion of a metal is 5.53 J/g at its freezing (melting) point of 559◦F. How much of this solid metal (already at 559◦F) can be melted if 3382 J of energy are available? Answer in units of g. I don't know how to set up the problem
Tuesday, April 14, 2015 at 6:55pm
I am working on a five-part question and I just need help with the last part. I'm not sure where to begin with that one. I pasted the question and answers (for a-d) to the other parts below. Thank you! Consider the proposed mechanism for the reaction between nitrogen ...
Tuesday, April 14, 2015 at 6:53pm
The electrophoresis of a mixture of histidine (His), aspartic acid (Asp) and phenylalanine (Phe) is carried out at a pH of 5.91. Match the amino acid to its predicted behaviour under electrophoresis at that pH. 1. This amino acid will bear no net charge at pH 5.91 and so will ...
Tuesday, April 14, 2015 at 4:40pm
One mole of an ideal gas is expanded from a volume of 1.00 atm. How much work (in joules) is performed on the surroundings? Ignore sig figs for this problem. (T=300 K; 1 L*atm=101.3 J)
Tuesday, April 14, 2015 at 2:46pm
It has been determined that the body can generate 5500 kJ of energy during one hour of strenuous exercise. Perspiration is the body's mechanism for eliminating this heat. How many liters of water would have to be evaporated through perspiration to rid the body of the heat ...
Tuesday, April 14, 2015 at 12:24pm
Consider the reaction 2D2(g)+O2(g)→2D2O(l) What is the mass of heavy water, D2O(l), produced when 7.65g of O2(g) reacts with excess D2(g)? Express your answer with the appropriate units.
Tuesday, April 14, 2015 at 10:48am
Balance the given chemical equation using whole-number coefficients. ?D2(g)+?O2(g)→?D2O(l) Enter the coefficients in order separated by commas (e.g., 1,3,2, where 1 indicates the lack of a coefficient).
Tuesday, April 14, 2015 at 10:47am
In the Sandwich Shop, select the "Cheese sandwich" option and observe the equation given for the preparation of a cheese sandwich. In the equation, set the number of bread slices to "2" and the number of cheese slices to "1." You will see that the...
Tuesday, April 14, 2015 at 10:46am
Find the number of moles of water that can be formed if you have 226mol of hydrogen gas and 108mol of oxygen gas. Express your answer with the appropriate units.
Tuesday, April 14, 2015 at 10:45am
To identify a diatomic gas (X2), a researcher carried out the following experiment: She weighed an empty 2.7-L bulb, then filled it with the gas at 1.30atm and 30.0 ∘C and weighed it again. The difference in mass was 3.9g . Identify the gas.
Tuesday, April 14, 2015 at 10:24am
The electrophoresis of a mixture of histidine (His), aspartic acid (Asp) and phenylalanine (Phe) is carried out a pH of 5.91. What amino acid will This bear no net charge at pH 5.91 and so will remain at the origin, carry a net negative charge at pH 5.91 and so will migrate ...
Tuesday, April 14, 2015 at 8:21am
An aqueous solution of a monoprotic acid is prepared. This acid is known to have a pKa of 8.6. If the acid is 37.5% ionized when in solution, what is the pH of the solution? Not really sure where to start with this question? Thanks in advance
Tuesday, April 14, 2015 at 8:20am
A helium balloon is filled to a volume of 5.60 L at 25∘C. What will the volume of the balloon become if it is put into liquid nitrogen to lower the temperature of the helium to 77 K? A helium balloon is filled to a volume of 5.60 at 25. What will the volume of the ...
Monday, April 13, 2015 at 11:21pm
A solution of a substance was spotted at a distance 0.5cm from the base of a 20cm long chromatographic plate.Upon elution,the solvent front got to a place 0.5cm from the top of the plate.If the component moves half way up the 20cm plate,calculate its Retention factor value.(...
Monday, April 13, 2015 at 4:39pm
Aqueous ammonia is commercially available at a concentration of 16.0 M. Part A How much of the concentrated solution would you use to prepare 500.0mL of a 1.30M solution?
Monday, April 13, 2015 at 12:01pm
What is the molarity of a solution 12.5 naoh dissolved in total volume of 625ml? NaOH = 12.5/molar mass of NaOH = 12.5/39.99 = 0.313 molarity = no.of moles/volume in L = 0.313/0.625 = 0.501 moles/L
Monday, April 13, 2015 at 11:42am
I know how to carry out an absorption spectrum I just need help on how to to prepare my test tubes and what to put in then. I am very confused and any help would be greatly appreciated. THANKS ! You will be given a sample containing an unknown concentration of protein (Bovine ...
Monday, April 13, 2015 at 2:15am
Chemistry (please Help!!)
determine which experiences a lower effective nuclear charge. using words and/ or drawings explain why. A) an electron in a 2s or an electron in a 2p B) a valence electron on sulfure or a vance electron on silicon C) a valence electron on chlorine or a valence electron on ...
Monday, April 13, 2015 at 1:34am
Consider the following description of a voltaic cell: A 1.0 M solution of Ni(NO3)2 is placed in a beaker with a strip of nickel metal. A 1.0 M solution of SnSO4 is placed in a second beaker with a strip of Sn. The two beakers are connected byba salt bridge and the two ...
Sunday, April 12, 2015 at 11:45pm
a chemist puts 50g of chemical a in beaker 1 and 25 g of chemical b in beaker 2 she places bot beaker into a larger container. as the chemicals evaporated the gas react into a white solid what mass of solid will form if chemicals react
Sunday, April 12, 2015 at 11:43pm
At room temperature (25 °C), the gas ClNO is impure because it decomposes slightly according to the equation 2ClNO(g) Cl2(g) + 2NO(g) The extent of decomposition is about 4%. Based upon this, what is the approximate value of ΔG°298 for the reaction at that ...
Sunday, April 12, 2015 at 9:12pm
Given these reactions and their corresponding ΔG° values, Glucose + phosphate → glucose-6-phosphate + H2O; ΔG° = +13.13 kJ ATP + H2O → ADP + phosphate; ΔG° = -32.22 kJ What is the calculated ΔG° for the coupled reaction Glucose...
Sunday, April 12, 2015 at 9:08pm
A half-cell that consists of a copper wire in 1.00 M CuNO3 solution is connected by a salt bridge to a half cell containing a 1.00 M X(II) acetate solution and an electrode of metal X. The voltage of the cell is 2.00 V, with metal X as the positive electrode. Calculate the ...
Sunday, April 12, 2015 at 8:26pm
Identify the correct statement for the following reaction: Br2 (l) → Br2 (g) ΔH° = 30.9 kJ ΔS° = 93.2 J/K A) The reaction is always spontaneous. B) The reaction is never spontaneous. C) The reaction is at equilibrium; therefore, ΔG° = 0. D) The...
Sunday, April 12, 2015 at 6:06pm
hi, need help.. use the atomic weight of carbon and chlorine to determine the theoretical value of the molecular weight of CH3OH(I've calculate the average mr of CH3OH -->0.39g/mol).(atomic weight: c= 12.0, cl= 35.5)
Sunday, April 12, 2015 at 5:46pm
calculate the volume of hydrogen produced when 6g of magnesium is reacted with 100cm of 1 mol l-1 hydrochloric acid no of moles of Mg= mass/gfm = 6/24.3 = 0.247 moles 1/2 mole of Mg= 1/2 mole of H2 = 0.247 moles x 100 = 24.7cm3 ???
Sunday, April 12, 2015 at 5:30pm
Chemistry - Help
Please help..Write the equation for the equilibrium constant (K) of the reaction. 2K2CrO4 + 2HCl --><-- Cr2O7 + H2O + 2KCl (K2CrO4 is chromate) and (Cr2O7 is dichromate)
Sunday, April 12, 2015 at 4:25pm
a 5.00 gram sample of a metal is heated to 80 degrees Celsius and is placed in a 100 gram sample of water. the temperature of the water rises from 20 Celsius to 20.3 Celsius which of these is most likely to be the metal
Sunday, April 12, 2015 at 12:44pm
What is the change in entropy when 9.30 mL of liquid benzene (C6H6, d = 0.879 g/mL) is burned in the presence of 37.2 L of oxygen gas, measured at 298 K and 1 atm pressure? 2C6H6(l) + 15O2(g) → 12CO2(g) + 6H2O(l); ∆S° = 437.7 J/K at 298 K
Saturday, April 11, 2015 at 8:08pm
Suppose 50mL of 8.4 x 10^-7 M Pb(NO3)2 (aq) is mixed with 200 mL of 9.7 x 10 ^-4 M Na2CO3 (aq). Calculate Q and determine whether a ppt of PbCO3(s) will form.
Saturday, April 11, 2015 at 8:02pm
A buffer with a pH of 4.30 contains 0.25 M of sodium benzoate and 0.20 M of benzoic acid. What is the concentration of [H ] in the solution after the addition of 0.052 mol of HCl to a final volume of 1.5 L? I know that Ka = 6.3x10-5 do I need to use an ice table or is the pH=...
Saturday, April 11, 2015 at 8:00pm
Consider this reaction: 3 K2CO3 (aq) + 2 CrCl3 (aq) -> Cr2(CO3)3 (s) + 6 KCl (aq) If 1.2 moles of CrCl3 react, how many moles of K2CO3 will react with it? A. 0.80 mol K2CO3 B. 1.2 mol K2CO3 C. 1.8 mol K2CO3 D. 2.4 mol K2CO3 I'm not sure where to even begin, I know how ...
Saturday, April 11, 2015 at 5:35pm
When a 100 mM aq solution of sodium acetate was prepared in the lab it had a pH of 8.9. Calculate the amount of acetic acid (in g) to be added to 0.5 L of this sodium acetate solution in order to bring its pH to the target value of 5.00.
Saturday, April 11, 2015 at 4:13am
Chemistry (solubility product question)
"When 3.00 ml of a 0.00600 M K2CrO4 solution and 3.000 ml of a 0.0100 M Cu(NO3)2 solution are mixed, some solid forms. The mixture is centrifuged and the supernatant is removed. The absorbance of the supernatant, measured at 400 nm in a 1.00 cm cuvette, is 0.286. The ...
Friday, April 10, 2015 at 10:55pm
I understand part (I) but We have only briefly gone over the HH equation in class and I understand how to use it to get the pH but I really don't understand how to use it in part (II), assuming I should be using it in this question? (I)Calculate the pH of an acetate buffer...
Friday, April 10, 2015 at 6:53pm
Gaseous ethane will react with gaseous oxygen to produce gaseous carbon dioxide and gaseous water . Suppose 16.2 g of ethane is mixed with 19. g of oxygen. Calculate the maximum mass of carbon dioxide that could be produced by the chemical reaction. Round your answer to ...
Friday, April 10, 2015 at 4:07pm
An optically active compound A, C6H10O2, when dissolved in NaOH solution, consumed one equivalent of base. On acidification, compound A was slowly regenerated. Treatment of A with LiAlH4 in ether followed by protonolysis gave an optically inactive compound B that reacted with ...
Friday, April 10, 2015 at 2:54pm
How much volume of a 1.5 M KOH is needed to extract a carboxylic acid from a mixture of 2.450 gram of benzoic acid and a 2.080 g of acetanilide? This is a liquid liquid extraction.
Friday, April 10, 2015 at 7:41am
For the weak hypochlorous acid (HClO), which statement is true at the point halfway to the equivalence point? A. The total amount of HClO is equal to the pKa. B. The total amount of HClO is equal to ClO-. C. The total amount of H3O+ is equal to the amount of OH- . D. The total...
Thursday, April 9, 2015 at 11:30pm
A 54.7-g sample of aluminum at 95.0°C is dropped into 35.0 g of water at 40.0°C. What is the final temperature of the mixture? (specific heat capacity of aluminum = 0.89 J/g°C; specific heat capacity of water = 4.184 J/g°C)
Thursday, April 9, 2015 at 11:19pm
Can you help me calculate the maximum weight-percent of H present in liquid iron containing 0.16 wt% Oxygen and equilibrated with H2O(g) at a pressure of 0.164 atm at 1600°C. Given ÄG° = -207653 + 0.292T J and assume that O and H both obey Henrys law.
Thursday, April 9, 2015 at 9:45pm
calculate oh- and ph in a solution in which dihydrogen phosphate ion is 0.335 M and hydrogen phosphate is 0.335 M. This is a homework question, where I have the solution, which is 0.335/0.335, which I get, but then I am supposed to multiply this (1)by a number 6.2x10-8? I have...
Thursday, April 9, 2015 at 5:23pm