I have 2 chem lab questions. the first one has tow part and I attached the experiment paper with the questions
1-what co cause the experimental wei to be
(a)lower than expected
(b)higher than expected (please not same explanation for both)
2-suppos the Mg used in the experiment had a thin oxide coating. how would this affect the ratio of moles of oxygen per mole of Mg (calcu quan in step 8) explain
pleas full answer as short as you can
please don’t si the hanf shak before being sure that you can do it right
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Describe the process that ice on Mount Everest goes through when being heated from 10 degrees Fahrenheit to 305 degrees Kelvin. Explain how the energy requirements change at different steps of the heating curve. What are the energy transfers that happen in the ice on Mount Everest?
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Consider the following equation for the production of NO2 from NO:
2 NO(g) + 02(g) ——> 2 NO2(g)
a. If 84.8 L of 02(g), measured at 35C and 632mm Hg, is allowed to react with 158.2 g of NO, find the limiting reagent.
b. If 97.3 L of NO2 forms, measured at 35C and 632mm Hg, what is the percent yield?
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Describe the use of radioactive tracers to detect and treat diseases
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a) The proton concentration of a solution is 0.0005 mole/l. What is the pH of this solution?
b) The hydroxide ion concentration of a solution is 0.0005 mole/l, what is the pH of this solution?
Problem 2
a) The pKa value for hypochlorous acid is 7.45, what is Ka value for the same acid?
b) The Ka value for acetic acid is 10-4.75, what is the pKa value for the same acid?
Problem 3
Examine dissociation of acetic acid (CH3COOH) and hydrochloric acid (HCl) at pH 5 and 10. – –
Calculate [Cl ]/[HCl] and [Ac ]/[HAc]
Problem 4
a) What is the oxidation states of sulfur in SO42- and HS- ? b) Balance the following redox reaction use the half reactions (you have to develop
the half reactions to get full credit)
SO42- + H+ + CH2O HS- + CO2 + H2O
Problem5
SO42- + H+ + 2CH2O HS- + 2CO2 + 2H2O In above balanced redox reaction, list the following:
Oxidant:
Reductant:
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I would like you to write three lab reports about three different experiments. I will upload you the instructions on how does the report have to be done. Also, I will upload you the experiment file ( this file will contain everything data, question and answers, purpose, etc..) I would like you to rewrite this answers I wrote on your own words. I will also upload you a sample for an old lab report. I want two pages for each experiment six in total. Thank you!
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Chemical nomenclature is an important skill that you will use outside of this class. In many ways, it is a primary skill needed in pharmacology and medicine. For example, a common imaging agent used for x-rays of the gastro-intestinal tract is barium sulfate. Despite the high toxicity of barium, barium sulfate (BaSO4) can be safely ingested because it does not dissolve well in water and passes through the intestines with little effect on the patient. In contrast, barium sulfite (BaSO3) dissolves in water much more easily and is highly toxic. Despite very similar names, barium sulfate versus barium sulfite, these chemicals give very different results.
For this discussion board, research (use more than one source) the chemical properties and safety concerns of one pair of chemicals (listed below) and create a thread to answer the following questions. Be sure to back up your responses with your sources. Once you have completed your post, respond to one additional student’s answer for question 4 with an additional example or consequence. This response should be to a different chemical pair than what you used.
This assignment is worth 10 points.
Chemical Pairs (Pick only one):
zinc phosphate versus zinc phosphide
potassium chloride versus potassium chlorate
aluminum hydroxide versus ammonium hydroxide
Questions: What are some of the common uses for each of the chemicals in your pair? What are some of the safety concerns for each of these chemicals? (It might help to look up the SDS for each chemical) How are the properties and safety concerns of these two chemicals different? Are they similar? What do you think could happen if you used the opposite chemical in one of the common uses you researched above? What are some of the consequences that could occur? Be sure to include an example for both chemicals you looked up.
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1. If 4.168 kJ of heat is added to a calorimeter containing 75.40 g of water, the temperature of the water and the calorimeter increases from 24.58 ° C to 35.82 ° C. Calculate the heat capacity of the calorimeter (in J/ ° C). The specific heat of water is 4.184 J/g• ° C.
a.
622 J/ ° C
b.
55.34 J/ ° C
c.
315.5 J/ ° C
d.
25.31 J/ ° C
e.
17.36 J/ ° C
2. How much heat is absorbed in the complete reaction of 3.00 grams of SiO2 with excess carbon in the reaction below? D H 0 for the reaction is +624.6 kJ.
SiO2(g) + 3C(s) ® SiC(s) + 2CO(g)
a.
366 kJ
b.
1.13 ´ 105 kJ
c.
5.06 kJ
d.
1.33 ´ 104 kJ
e.
31.2 kJ
3. How much heat is released when 75 g of octane is burned completely if the enthalpy of combustion is -5,500 kJ/mol C8H18?
C8H18 + 25/2 O2 ® 8CO2 + 9H2O
a.
7200 kJ
b.
8360 kJ
c.
4.1 ´ 105 kJ
d.
3600 kJ
e.
5500 kJ
4. The burning of 80.3 g of SiH4 at constant pressure gives off 3790 kJ of heat. Calculate D H for this reaction.
SiH4(g) + 2O2(g) ® SiO2(s) + 2H2O(l)
a.
-1520 kJ/molrxn
b.
– 47.2 kJ/molrxn
c.
– 4340 kJ/molrxn
d.
-2430 kJ/molrxn
e.
+ 4340 kJ/molrxn
5. Which of the following statements is incorrect?
a.
The thermochemical standard state of a substance is its most stable state under one atmosphere pressure and at some specific temperature (298 K if not specified)
b.
A superscript zero, such as D H 0 , indicates a specified temperature of 0 ° C.
c.
For a pure substance in the liquid or solid phase, the standard state is the pure liquid or solid.
d.
For a pure gas, the standard state is the gas at a pressure of one atmosphere.
e. For a substance in solution, the standard state refers to one-molar concentration.
6. For which of the following substances does = 0?
a.
CO2(g)
b.
H2O(g)
c.
Na(s)
d.
Br2(g)
e.
C(diamond)
7. Calculate the amount of heat released in the complete combustion of 8.17 grams of Al to form Al2O3(s) at 25 ° C and 1 atm. D H for Al2O3(s) = 1676 kJ/mol
4Al(s) + 3O2(g) ® 2Al2O3(s)
a.
254 kJ
b.
203 kJ
c.
127 kJ
d.
237 kJ
e. 101 kJ
8. Which of the following is not a formation reaction?
a.
1/2H2(g) + 1/2 Br2(l) ® HBr(g)
b.
H2(g) + 1/2O2(g) ® H2O(l)
c.
Ca(s) + 1/2O2(g) ® CaO(s)
d.
4Al(s) + 3/2O2(g) ® Al2O3(s)
e.
H2O(l) + SO3(l) ® H2SO4(l)
9. Given the standard heats of formation for the following compounds, calculate D H for the following reaction.
CH4(g)
+ H2O(g)
®
CH3OH(l)
+ H2(g)
D H (kJ/mol)
-75
-242
-238
0
a.
+79 kJ
b.
-79 kJ
c.
+594 kcal
d.
-594 kcal
e. – 405 kJ
10. Given the following at 25 ° C, calculate D H for HPO3(s) at 25 ° C.
P4O10(s) + 4HNO3(l) ® 4HPO3(s) + N2O5(s)
D H = -180.6 kJ
D H = -2984 kJ/mol for P4O10(s), -174.1 kJ/mol for HNO3(l), and – 43.1 kJ/mol for N2O5(s).
a.
-528.0 kJ/mol
b.
-1474 kJ/mol
c.
-948.5 kJ/mol
d.
+1474 kJ/mol
e. -954.5 kJ/mol
11. How much heat is released when 6.38 grams of Ag(s) reacts by the equation shown below at standard state conditions?
4Ag(s) + 2H2S(g) + O2(g) ® 2Ag2S(s) + 2H2O(l)
Substance
Ag(s)
0
H2S(g)
-20.6
O2(g)
0
Ag2S(s)
-32.6
H2O(l)
-285.8
a.
8.80 kJ
b.
69.9 kJ
c.
22.1 kJ
d.
90.8 kJ
e. 40.5 kJ
12. Which of the following techniques cannot be used to calculate D Hrxn?
a.
Calorimetry
b.
Using melting points of reactants and products
c.
Hess’s Law
d.
Using of Heats of Formation of reactants and products
e. Using bond energies of reactants and products
13. Evaluate D H 0 for the following reaction from the given bond energies.
2HBr(g) ® H2(g) + Br2(g)
D H H-H = 436 kJ/mol, D H Br-Br = 193 kJ/mol, D H H-Br = 366 kJ/mol
a.
-103 kJ
b.
-143 kJ
c.
+103 kJ
d.
+142 kJ
e. 259 kJ
14. A positive change in entropy represents:
a.
an increase in molecular disorder
b.
release of thermal energy
c.
a decrease in thermal energy
d.
a process that is always spontaneous
e. a process that cannot occur spontaneously
15. The second law of thermodynamics states:
a.
All exothermic processe s also increase entropy.
b.
The enthalpy of the universe always increases in spontaneous processes.
c.
A spontaneous process always increases entropy.
d.
D H <0 and D S >0 for all spontaneous processes
e. The entropy of the universe always increases in spontaneous processes.
16. What is the entropy change of the reaction below at 298 K and 1 atm pressure?
N2(g)
+ 3H2(g)
®
2NH3(g)
S (J/mol · K)
191.5
130.6
192.3
a.
-198.7 J/K
b.
76.32 J/K
c.
-129.7 J/K
d.
303.2 J/K
e. 384.7 J/K
17. The heat of vaporization of methanol, CH3OH, is 35.20 kJ/mol. Its boiling point is 64.6 ° C. What is the change in entropy for the vaporization of methanol?
a.
-17.0 J/mol•K
b.
3.25 J/mol•K
c.
17.0 J/mol•K
d.
104 J/mol•K
e. 543 J/mol•K
18. Which of the following statements regarding the third law of thermodynamics is incorrect ?
a.
The absolute S is zero at 0 Kelvin.
b.
The absolute S at 298 K can be positive or negative.
c.
Pure substances have positive absolute S at T > 0 Kelvin.
d.
Absolute zero gives a reference point for determining absolute S.
e. The absolute S is greater at 300 K than 100 K for a given substance.
19. Which of following would have the highest value of absolute entropy per mole?
a.
water at 50 ° C
b.
water at 10 ° C
c.
ice at -10 ° C
d.
1 MNaCl at 50 ° C
e. 1 MNaCl at 10 ° C
20. Based on the relationship of entropy to the degree of disorder in a system, which response includes all the following changes that represent an increase in entropy, and no others?
I.
the freezing of water
II.
the condensation of steam
III.
sublimation (vaporization) of dry ice, solid CO2
IV.
the extraction of salts and pure water from seawater
a.
I and IV
b.
II and IV
c.
I, and II
d.
III
e. I and III
21. Which response includes all the following processes that are accompanied by an increase in entropy, and only those processes?
I.
boiling water
II.
freezing water
III.
N2(g) + 3H2(g) ® 2NH3(g)
IV.
Br2(l) ® Br2(g)
a.
I and II
b.
III and IV
c.
I and IV
d.
II, III, and IV
e. another one or another combination
22. Which of the following changes represent a decrease in entropy?
a.
Precipitation of CaCO3 to form a seashell
b.
Evaporation of gasoline
c.
Decomposition of a dead animal
d.
Melting snow
e. Diffusion of perfume throughout a room.
23. Consider the conversion of a substance from solid to liquid.
Solid Liquid
At one atmosphere pressure and at the melting point of the substance, __________.
a.
D H = 0 for the process
b.
D S = 0 for the process
c.
D E = 0 for the process
d.
D G = 0 for the process
e. both D H = 0 and D E = 0 for the process
24. Evaluate D G 0 for the reaction below at 25 ° C.
2C2H2(g)
+ 5O2(g)
®
4CO2(g)
+ 2H2O(l)
D G (kJ/mol)
209.2
0
-394.4
-237.2
a.
-1409 kJ
b.
-2599 kJ
c.
-1643 kJ
d.
-2470 kJ
e. -766 kJ
51. Calculate D G 0 at 298 K for the reaction below.
Fe2O3(s)
+ 13CO(g)
®
2Fe(CO)5(g)
+ 3CO2(g)
D H (kJ/mol)
-824.2
-110.5
-733.8
-393.5
S 0 (J/mol•K)
87.4
197.6
445.2
213.6
a.
+63.6 kJ
b.
+26.8 kJ
c.
-243.1 kJ
d.
-52.2 kJ
e. -193.3 kJ
52. The standard molar enthalpy of formation of NO2(g) is 33.2 kJ/mol at 25 ° C and that of N2O4(g) is 9.16 kJ/mol. At 25 ° C their absolute entropies are 240.0 and 304.2 J/mol•K, respectively. Use the above data to calculate the standard Gibbs free energy change for the following reaction at 25 ° C. Express your answer in the form D G 0 = __________ kJ.
N2O4(g) ® 2NO2(g)
a.
4.1 kJ
b.
21.3 kJ
c.
4.8 kJ
d.
41.5 kJ
e. 11.4 kJ
53. For which set of values of D H and D S will a reaction be spontaneous (product-favored) at all temperatures?
a.
D H = +10 kJ, D S = -5 J/K
b.
D H = -10 kJ, D S = -5 J/K
c.
D H = -10 kJ, D S = +5 J/K
d.
D H = +10 kJ, D S = +5 J/K
e.
no such values exist
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is the stability of a nucleus determined by the ratio of electrons to protons?
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