Recent Homework Questions About Chemistry
A 200.0g sample of glucose(180.16g/mol, Kmp=1.86 degrees celcius/m, mp=146 degrees celcius)is contaminated with 5.000g of table salt, sodium chloride(58.44g/mol, mp=801 degrees celcius). What would the expected melting point of the mixture be?
Sunday, September 7, 2014 at 2:17am
which pairing below does not correctly match the scientist with the contribution to the understanding of the atom A. Proust and the realization that the elements of compounds are found in certain proportions by mass B. Thomson and the law of definite proportions. C. Dalton and...
Sunday, September 7, 2014 at 1:43am
which of the following statements correctly describes energy levels? A. Electrons can never move to a higher or lower energy level. B. In its outermost energy level, oxygen has 4 valence electrons C. The Second energy level holds a maximum of eight electrons. D. The greater ...
Saturday, September 6, 2014 at 10:43pm
determine the location of the non significant zeros by rewriting the number and placing a bar over the zeroes that are not significant. 1. 8040 2. 4.2 x 10^5 3. 4.70 x 10^-6
Saturday, September 6, 2014 at 9:25pm
Give the number of significan figures and decimal places in each of the following: 1. 80750 X 10^-2 2. 9.9000 X 10^8 3. 30.366 X 10^4 cm^3 4. 0.11692 X 10^-5
Saturday, September 6, 2014 at 8:29pm
Find the pH of 1.0E-8 M H2S04 (H2SO4 <==> 2H^+ + SO4^2-) I have got answer to be 7.70, can you confirm the answer for me please? If it is not good, i'll be very grateful if you could leave some guides.
Saturday, September 6, 2014 at 3:49pm
A gold nugget that weighs 20.053 g on the balance is lowered into a graduated cylinder filled with ethanol. If the initial ethanol level was 10.10 mL, what will the final ethanol level be?
Saturday, September 6, 2014 at 11:08am
A gold cube that measures 3.00 cm on each side is lowered into a volumetric cylinder that has an initial reading of 5.75 mL. What will be the new water level?
Saturday, September 6, 2014 at 11:07am
A farmer supplies 1250.0 kg of a fertilizer that contains 10& nitrogen to his fields each year. Fifteen percent of the fertilizer washes into a river that runs through the farm. If the river flows at an average rate of 0.165 cubic feet per second, what is the additional ...
Saturday, September 6, 2014 at 12:40am
You weigh an empty dish and find its mass to be 48.0 grams. After you add a volume of salt water to the dish the mass of the dish and salt water is now 74.0 grams. After 100% of the water has been evaporated, the mass of the dish and the remaining salt is 52.5 grams. What is ...
Friday, September 5, 2014 at 10:37pm
The average cooling rate of a cup of coffee is 24 °C per minute, and you can begin to sip the coffee when it is 60 °C. How long must you wait before you can begin to sip the coffee if the initial coffee temperature is 156 °C?
Friday, September 5, 2014 at 10:20pm
Density (d) is mass (m) divided by volume (V) (d = mV). Mass is typically measured in grams (g), while volume is typically measured in milliliters (mL). How much volume will 550 g of a solution with a density of 1.10 g/mL occupy?
Friday, September 5, 2014 at 10:17pm
Flask A contains 100 milliliters of a solution with a pH of 5. After you add 100 milliliters of a solution from Flask B, the pH rises to 7. What was the pH of the solution in Flask B?
Friday, September 5, 2014 at 9:04pm
a solution of OH- ions is added to a beaker of pure water at 25 C, to a final concentration of 872 nM. Calculate the pH of the solution. I know that pH=-log[H+], but I'm still really confused as to how to convert the nM to M and how to solve this problem.
Friday, September 5, 2014 at 3:42pm
If I count out Avogadro's number if CO2 molecules how much will my piles of molecules weigh? Can someone show me how to get the answer. I know the answer is 44g
Thursday, September 4, 2014 at 11:43pm
a mixture of gases is prepared for laboratory experiments by combining 4.2 L of oxygen, 0.71 L of nitrogen, and 0.22 L of carbon dioxide. Determine the percentage of nitrogen in the mixture.
Thursday, September 4, 2014 at 9:22pm
What will be the freezing point of a solution made by dissolving 5.25 g of naphthalene (C10H8) in 100.0 g benzene (C6H6?). The normal freezing point of benzene is 5.5°C and K f (benzene) is 5.12°C / m.
Thursday, September 4, 2014 at 7:06pm
A 6.8 g sample of metal pellets is placed into a graduated cylinder holding 7.1 ml of water. After the pellets are added, the water level stands at 9.30 ml. Determine the density of the pellets. (show all work) I've tried 6.8 g / 9.30 ml and .97-.71 to get .24 but I'm ...
Thursday, September 4, 2014 at 5:47pm
a concentration-time study of the gas phase reaction a 2A3 -> 3A2 produced the data in the table below. time [A3] (M) [A2] (M) 0 4.00 *10^-4 0 10 2.00 *10^-4 3.00 *10^-4 20 1.00 *10^-4 4.50 *10^-4 10 5.00 *10^-5 ? A) What is the concentration of A2 in the time interval 20-...
Thursday, September 4, 2014 at 2:48pm
A patient receives 2700mL of an IV solution containing 4g g of glucose per 100 mL .How much energy, in kilojoules, does the patient obtain from glucose, a carbohydrate? please help I keep getting the wrong answer
Thursday, September 4, 2014 at 2:36pm
a chemical reaction released 50.0kJ of energy as it heated a sample of water from 17.0 degrees celsius to 75.0 degrees Celsius, what mass of water was heated? I have no clue as to how to do this! can anyone help?
Thursday, September 4, 2014 at 8:24am
nitrosyl bromide, NOBr is formed from NO and Br2-. Experiments show that this reaction is second order in NO and first order in Br2. what is the rate equation for this reaction?
Wednesday, September 3, 2014 at 6:30pm
'A patient receives 2900mL of an IV solution containing 3g of glucose per 100 mL. How much energy, in kilocalories, does the patient obtain from glucose?
Wednesday, September 3, 2014 at 6:13pm
A container is fabricated from steel having a thickness of 0.500 inch and an average density of 7.85 g/cm3. (You may assume that the container is cylindrical with hemispherical ends.) What is the mass of the filled container, assuming that liquid propane has a density of 0....
Wednesday, September 3, 2014 at 5:29pm
Suppose there are two known compounds containing the generic elements X and Y. You have a 1.00-g sample of each compound. One sample contains 0.29 g of X and the other contains 0.38 g of X. Identify plausible sets of formulas for these two compounds. Check all that apply. XY ...
Wednesday, September 3, 2014 at 3:57pm
A syrup is added to an empty container with a mass of 102.00g . When 0.133 pint of syrup is added, the total mass of the container and syrup is 196.34g . (1 qt = 2 pt)
Wednesday, September 3, 2014 at 3:28pm
Naturally occurring cobalt consists of only one isotope, 59Co, whose relative atomic mass is 58.9332. A synthetic radioactive isotope of cobalt, 60Co, relative atomic mass 59.9338, is used in radiation therapy for cancer. A 1.8276g sample of cobalt has an apparent "atomic...
Wednesday, September 3, 2014 at 3:01pm
When a 1.1 gram ice cube is placed into a 10.0 mL graduated cylinder, the level of water inside the graduated cylinder raises 1.20 mL. What is the Density of the ice cube? My Work: Density = 1.1g/10.0 mL + 1.20 mL? my answer came out to be; Density= .0982 g/mL
Wednesday, September 3, 2014 at 12:17am
For a carbon atom that is sp2 hybridized, I understand that the electron configuration would be Yes, 1s2 2s1 2p3 which is a 2s up arrow,and 3 orbtials that are 2p up arrows but then since the four bonds hybridize to form four sp3 hybrid bonds how do I write this? Also for an ...
Tuesday, September 2, 2014 at 11:33pm
Question: how do you dilute something with a huge concentration to the same thing with a smaller concentration? For example: How do you dilute a 36 M solution of NaOH to a 6 M solution of NaOH?
Tuesday, September 2, 2014 at 10:26pm
Analytical Chemistry question: Find the pH and the concentration of each species of lysine in a solution of 0.0010 M lysine*HCL. I know that the pKAs of lysine are (1.77)(CO2H) 9.07 (-NH3) 10.82 ( -NH3) but I am not sure where to go from there.
Tuesday, September 2, 2014 at 9:58pm
Which of the following statements correctly describes energy levels? A. Electrons can never move to a higher or lower energy level. B. In its outermost energy level, oxygen has 4 valence electrons C. The second energy level holds a maximum of eight electrons. D. The greater ...
Tuesday, September 2, 2014 at 9:27pm
We did not find any results for 'if the solubility of cuso4.5H2O at 30 degree celcus is 25 gram per 100gram of H2O.what is the maximum mass of crystal that will be obtained from 10gram?
Tuesday, September 2, 2014 at 4:19pm
Suppose you have two 100-mL graduated cylinders. In each cylinder there is 40.0mL of water. You also have two cubes: one is lead(11.3g/ml), and the other is aluminum(2.70g/ml) Each cube measures 2.0cm on each side. After you carefully lower each cube into the water of the ...
Tuesday, September 2, 2014 at 2:11pm
2) Calculate the following properties of 2,4,6-trichlorophenol (C6H3Cl3O) at 25ºC: - Diffusion coefficient in water (cm2/s) - Henrys constant [(atm·m3)/mol] - Henrys constant (dimensionless) Given information: - Universal gas constant (R) = 0.082 atm&...
Tuesday, September 2, 2014 at 9:14am
When 62.1 moles of calcium acetate are dissolved in enough water to make 585.1 milliliters of solution, what is the molarity of acetate ions? Answer in units of M
Monday, September 1, 2014 at 11:32pm
Fannie eats a dozen doughnuts every 36 hours. How many doughnut does she eat in a week? I used Dimensional Analysis(which isn't helping at all), but it keeps giving me weird number, like 36 over 2016 or 252 over 2016.
Monday, September 1, 2014 at 9:13pm
Block A of an unknown metal has a volume of 125 cm3. Block B of a different metal has a volume of 145 cm3. If block A has a greater mass than block B, what can be said of the relative densities of the two metals? (Assume that both blocks are solid.)
Monday, September 1, 2014 at 7:53pm
1.15g of acetylsalicylic ia recovered from an aspirim synthesis reaction that began with 2g of salicylic acid, what would be the percentage yield for the preparation? show your computations
Monday, September 1, 2014 at 6:08pm
Please give me a score of 1-6 (one being poor and six being excellent). Also, please give me some feedback! Thank you in advance! Essay prompt: What motivates people to change? Essay: Many people know that eating junk food is unhealthy. Yet, they keep eating it because it ...
Monday, September 1, 2014 at 1:13pm
I am having trouble figuring out the electron configuration for a carbon atom when it is in a molecule such as methane. I know that the ground state configuration for carbon is 1s2 2s2 2p2 but im not sure how to figure it out when it is bonded to other atoms. Thank you for the...
Monday, September 1, 2014 at 12:43am
Suppose that the dot/area representing the longest wavelength of color in this situation was located 21 mm from the baseline, and the dot/area representing the shortest wavelength of color was located 36 mm from the baseline (see Figure 9.4 on page 288 for help). If the ...
Sunday, August 31, 2014 at 2:45pm
I am unsure how to write hypotheses for my experiments for pH, salinity using tirration(agno3), turbidity, conductivity of water samples. The teacher wants the hypothesis in this format Hypothesis format - If (relationship between independent variable and dependent variable) ...
Sunday, August 31, 2014 at 7:38am
What is the pH of a solution prepared by dissolving 1.23g of 2-nitrophenol (FM 139.11) in 0.250 L? Well so, i calculated the no.moles of 2-nitrophenol, and divided it by 0.250, to get the molarity which was 3.53E-2. Since the molar ratio of dissociation is 1:1, i assumed [H+] ...
Sunday, August 31, 2014 at 7:28am
The following equilibrium partial pressures were measured at 750 deg C. PH2=0.387atm,PCO2=0.152atm,PCO= 0.180 atm,and PH2O=0.252atm. What is the value of the equilibrium constant Kp for the reaction? H2+CO2 ====CO+H2O
Saturday, August 30, 2014 at 11:24pm
At 25 deg C, Kc is 5.84x10-3 for the dissociation of dinitrogen tetraoxide to nitrogen dioxide. N2O4(g) ==== 2NO2(g) a) Calculate the equilibrium concentration of both gases when 4.00 grams of N2O4 is placed at 2.00-liter flask at 25 deg C. b) What will be the new equilibrium ...
Saturday, August 30, 2014 at 11:20pm
At some temperature,the reaction PCl3(g) +Cl2(g) ====PCl5(g) is at equilibrium when the concentration of PCl3, Cl2, and PCl5 are 10, 9.0, and 12mol/L, respectively. Calculate the value of Kc for this reaction at that temperature.
Saturday, August 30, 2014 at 11:16pm
calculate the mass of carbon dioxide that would be produced when one gas of tank of gasoline (use octane) is burned in the air. assume an 80 liter gas tank and 0.703 g/ml as the density of octane
Saturday, August 30, 2014 at 12:35pm
A student has repeated the hydrolysis experiment with 2-iodo-2-methylpropane as the alkyl halide and found that the time to colour change was too fast to measure easily. Suggest two ways in which the reaction could be slowed down and by what process the slowing is happening in...
Saturday, August 30, 2014 at 8:26am
A first order reaction and a separate second order reaction both have the same rate of reaction. What is the effect on the rate of reaction for each reaction if the concentrations of reactants in both reactions are halved?
Saturday, August 30, 2014 at 7:50am
Gallium is a metal with a wide variety of uses. Some of its applications include computer memory chips, light emitting diodes and lasers. Radioactive isotopes of gallium are used to image the human body and locate tumors. Naturally occurring gallium consists of two isotopes. ...
Friday, August 29, 2014 at 8:40pm
In the combustion of hydrogen gas, hydrogen reacts with oxygen from the air to form water vapor. If you burn 54.8 g of hydrogen and produce 4.90 × 102 g of water, how much oxygen reacted?
Friday, August 29, 2014 at 5:11pm