A compound contains only carbon, hydrogen, nitrogen, and oxygen. Combustion of a 2.18 g sample burns in excess oxygen yields 3.94 g of CO2 and 1.89 g of H2O. A separate experiment shows that a 1.23 g sample contains 0.235 g of N. Calculate the moles of C in the sample.1. Calculate the moles of N for a 2.18 g sample (the sample size for the other analyses).
2. Calculate the moles of O in the sample.
Answers
Answer:
The answers are
C = 0.0895 moles
1. 0.02975 moles of N
2. 0.0299 moles O
Explanation:
Mass of sample = 2.18 g
Combustion yields 3.94 g of CO₂ and 1.89 g of H₂O
1.23 g of sample contains 0.235 g of N
3.94 g of CO₂ which contains one mole of C and two moles of O
Molar mass of CO₂ = 44 mass fraction of C = 12/44 = 0.273, Therefore mass of carbon in 2.18 g = 0.273×3.94 = 1.075 g
number of moles of C in sample = mass/(molar mass) = 1.075 g/(12.01 g/mol) = 0.0895 moles of C
(1) Mass of nitrogen, in 1.23 g of sample = 0.235
therefore mass in 2.18 g =0.235×2.18/1.23 = 0.4165 g
= 0.02975 moles of N
(2) To find the number of moles of oxygen in the sample we note that total mass of sample = 2.18 g containing only nitrogen, hydrogen, oxygen and carbon
Mass of hydrogen can be fround from 2/18×1.89 = 0.21 g
Mass of oxygen therefore = 2.18 -(0.21+0.4165+1.075) = 0.4785
number of moles = 0.475/16 = 0.0299 moles
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Without the sun, life on earth would not exist. There would be no warmth, no plants, no animals, no night and day. To power itself, the sun is constantly generating a nuclear reaction in its core, in which hydrogen nuclei are combined to form helium. This process is known as __________. A) fusion B) fission C) radiance D) solar flaring
An aqueous solution has a hydroxide-ion concentration of 1.0 x 10-3M. What is the pH of the solution? a 7 b -3 c 11 d 3
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Answers
Answer:
Explanation:
Given parameters:
Mass of ionic compound = 0.3257g
Mass of AgBr precipitate = 0.7165g
Unknown:
Percent mass of Br in the original compound.
Solution
The percent mass of Br in original compound =
Now we have to find the mass of Br⁻:
We must note that the same mass of Br⁻ would move through the ionic sample to form the precipitate.
Mass of Br in AgBr =
Mass of Br = x 0.7165
Mass of Br = 0.426 x 0.7165 = 0.305g
Percent mass of Br = x 100 = 93.7%
Answers
Answer:
1. D. cal......
2.A. iron
3. D
4.2.44j/g°C A
5,Lf=334J/g B
Explanation:
1: Which of the following is the abbreviation for a unit of energy? A. K / B. °C/ C. W / D. cal...............
calorie is the unit of energy
#2: A 200 g block of a substance requires 1.84 kJ of heat to raise its temperature from 25°C to 45°C. Use the table attached to identify the substance. A. iron/ B. aluminum/ C. gold/ D. copper.....................
Q=mcdt
1840=0.2*C*(45-25)
C=460J/KgK
if the specific heat capacity is the above then he substance is iron
#3: In a calorimeter, the temperature of 100 g of water decreased by 10°C when 10 g of ice melted. How much heat was absorbed by the ice? A. 418 kJ / B. 100 kJ / C. 10 J / D. 4.18 kJ .................
Q=mcdT
Q=0.1*10*4180
Q=4180j. answer D
.#4: The amount of heat needed to raise the temperature of 50 g of a substance by 15°C is 1.83 kJ. What is the specific heat of the substance? A. 2.44 J/g-°C / B. 2.22 J/g-°C / C. 2.13 J/g-°C / D. 2.05 J/g-°C ................
Q=mcdT
1830=50/1000*C*15
C=2440j/kg/k
change it to j/g°C
2.44j/g°C A
#5: In a calorimeter, 3.34 kJ of heat was absorbed when 10 g of ice melted. What is the enthalpy of fusion of the ice? A. 6.68 J/g / B. 334 J/g / C. 6.68 kJ/g/ D. 334 kJ/g
Q=mLf
Lf=enthalpy of fusion
3340/10=Lf
Lf=334J/g B
Enthalpy of fusion quantity of heat to convert 1 unit mass of a solid to liquid without any noticeable change in temperature.
formation of these mountains?
O The crust is compressed
O The crust does not spread apart
The center block is forced upward.
The hanging walls from the two parallel faults slip down
Answers
The Formation of these mountains will be caused by
- The crust does not spread apart
- The center block is forced upward.
- The hanging walls from the two parallel faults slip down
Options B, C, and D is correct.
What are mountains?
Generally, a mountain is simply defined as a body that rises dramatically above its surroundings and is distinguished by steep slopes.
In conclusion, Mountains are formed from the formation of rocks over years in an Environment.
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Answer:
d.
Explanation:
Answers
A digital thermometer is more preferable than a liquid-based thermometer because it gives accurate data than the liquid thermometer. Liquid thermometer is affected by the temperature, and when it does, the liquid expands and so des the material covering the thermometer. For the digital thermometer, it has less error because it already has a sensor inside it that determines the temperature of the substance.
B. Neon, atomic number 10
C. Fluorine, atomic number 9
D. Carbon, atomic number 6
Answers
Answer: Option (B) is the correct answer.
Explanation:
An atom is stable when it has completely filled orbitals. This means that K shell have 2 electrons, L shell have 8 electrons, M shell have 18 electrons and so on.
Therefore, electronic distribution of given elements will be as follows.
Boron has electronic configuration 2, 3.
Neon has electronic configuration 2, 8.
Fluorine has electronic configuration 2, 7.
Carbon has electronic configuration 2, 4.
Therefore, out of the given elements neon is stable.
The element that is stable among the options given is B. Neon, with atomic number 10.
Which is stable element?
Stability in the context of elements refers to having a filled outer electron shell, typically with eight electrons, known as an octet. Neon, a noble gas, has a complete octet with two electrons in the first shell and eight electrons in the second shell.
In contrast, elements like Boron (atomic number 5), Fluorine (atomic number 9), and Carbon (atomic number 6) do not have a complete octet in their outermost electron shells. They tend to form chemical bonds and engage in chemical reactions to achieve a stable electron configuration. Option B
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Answers
Answer: (E) Phosphorus
Explanation: PLATO
Answer:
E.
Explanation: