Answer:
K should be large so the temperature change will be large enough to measure.
Explanation:
Let us recall that;
∆T = k m I
Where;
∆T= change in boiling point
K= freezing point constant
m= molality
i= Van't Hoff factor
Since the change in temperature depends on k, the larger the value of k the larger the temperature change(Ts - Tb). Hence; K should be large so the temperature change will be large enough to measure.
Ts= freezing temperature of pure solvent
Tb= freezing temperature of solution
A quantity of 1.435 g of naphthalene , was burned in a constant-volume bomb calorimeter. Consequently, the temperature of the water rose from 20.28oC to 25.95oC If the heat capacity of the bomb plus water was , calculate the heat of combustion of naphthalene on a molar basis; that is, find the molar heat of combustion.
Answer:
molar heat of combustion = -5156 *10³ kJ/mol
Explanation:
A quantity of 1.435 g of naphthalene , was burned in a constant-volume bomb calorimeter. Consequently, the temperature of the water rose from 20.28oC to 25.95oC If the heat capacity of the bomb plus water was 10.17 kJ/°C, calculate the heat of combustion of naphthalene on a molar basis; that is, find the molar heat of combustion.
Step 1: Data given
Mass of naphthalene = 1.435 grams
Initial temperature of water = 20.28 °C
Final temperature of water = 25.95 °C
heat capacity of the bomb plus water was 10.17 kJ/°C
Molar mass naphtalene = 128.2 g/mol
Step 2:
Qcal = Ccal * ΔT
⇒with Qcal =the heat of combustion
⇒with Ccal = heat capacity of the bomb plus water = 10.17 kJ/°C
⇒with ΔT = the difference in temperature = T2 - T1 = 25.95 - 20.28 = 5.67°C
Qcal = 10.17 kJ/°C * 5.67 °C
Qcal = 57.7 kJ
Step 3: Calculate moles
Moles naphthalene = 1.435 grams / 128.2 g/mol
Moles naphthalene = 0.01119 moles
Step 4: Calculate the molar heat of combustion
molar heat of combustion = Qcal/ moles
molar heat of combustion = -57.7 kJ/ 0.01119 moles
molar heat of combustion = -5156 *10³ kJ/mol
Is it better to use graphite or carbon electrodes during electrolysis if I am trying to investigate volume of gas produced ?
Answer:
yes
Explanation:
it is important for electrolysis
what the movement of the earth around the sun
Answer:
Yan po Ang sagot NASA pic
Explanation:
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CORRECT ME IF IM WRONG
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Answer:
The movement of the earth around the sun in a fixed path or orbit is called Revolution. The axis of the earth which is an imaginary line, makes an angle of 66½° with its orbital plane. ... The earth takes about 24 hours to complete one rotation around its axis.
What is the mass number of an ion with 106 electrons, 157 neutrons, and a +1 charge?
Answer:
264 g/mol
Explanation:
#electrons equal #protons = 106
Plus 1 charge => m protons = 106 + 1 = 107
Mass number: 107 + 157 = 264 g/mol
Ammonia is produced by the reaction of nitrogen and hydrogen: N2(g) + H2(g) NH3(g)
(a) Balance the chemical equation.
(b) Calculate the mass of ammonia produced when 35.0g of nitrogen reacts with hydrogen.
Answer:
a) N2 (g) + H2 = 2 NH3
b) You have to state the mass of hydrogen
The products obtained from hydroboration-oxidation of cis-2-butene are identical to the products obtained from hydroboration-oxidation of trans-2-butene. Draw the products and explain why the configuration of the starting alkene is not relevant in this case.
Answer:
a) Attached below
b) The presence of racemic mixture found as product in both cases shows that products are identical ( i.e. they have same configuration
Explanation:
Diagrams of the products obtained from hydroboration-oxidation of cis-2-butene , hydroboration-oxidation of trans-2-butene.
attached below
The presence of racemic mixture found as product in both cases shows that products are identical ( i.e. they have same configuration )
Identify a process that is NOT reversible. Identify a process that is NOT reversible. melting of snow baking of bread deposition of carbon dioxide freezing water melting of aluminum
Answer:
Identify a process that is NOT reversible.
Melting of snow
baking of bread
deposition of carbon dioxide
freezing water
melting of aluminum
Explanation:
A physical change is the one in which there is a change only in its physical state, color, the appearance of the substance. But the chemical composition of the substance remains unchanged.
It is a temporary change and can be reversed easily.
For example:
melting, freezing, deposition etc.
Baking is a permanent change and the chemical composition of the substance changes.
Hence, among the given options, baking of bread is not a reversible change.
Out of the following all are physical changes except baking of bread and physical changes are reversible so the process which is not reversible is baking of bread.
What are physical changes?Physical changes are defined as changes which affect only the form of a substance but not it's chemical composition. They are used to separate mixtures in to chemical components but cannot be used to separate compounds to simpler compounds.
Physical changes are always reversible using physical means and involve a change in the physical properties.Examples of physical changes include melting,boiling , change in texture, size,color,volume and density.Magnetism, crystallization, formation of alloys are all reversible and hence physical changes.
They involve only rearrangement of atoms and are often characterized to be changes which are reversible.
Learn more about physical changes,here:
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Please help help please
Answer: The correct answer is B.
Explanation: Segregate most organic acids from oxidizing mineral acids. Keep oxidizers away from other chemicals, especially flammables.
Answer:
Segregate most organic acids from oxidizing mineral acids. Keep oxidizers away from other chemicals, especially flammables, combustibles, and toxic materials. Keep corrosives away from substances that they may react with and release corrosive, toxic, or flammable vapors.
g Calculate the theoretical yield (in grams) of your product if you start with 0.50 grams of E-stilbene. The molecular weight of E-stilbene is 180.25 g/mol, and the molecular weight of the product is 340.058 g/mol. 0.5109 grams 0.9433 g 0.2342 g 0.6312 g
Answer:
0.9433g
Explanation:
Theoretical yield is defined as the mass produced assuming all reactant reacts producing the product.
Assuming the reaction is 1:1, we need to find the moles of E-stilbene (Reactant). If all reactant reacts, the moles of E-stilbene = Moles of product.
Using the molar mass of the product we can find the theoretical yield as follows:
Moles E-stilbene:
0.50g * (1mol/180.25g) = 0.00277 moles = Moles Product
Mass Product = Theoretical yield:
0.00277 moles * (340.058g/mol) = 0.9433g
In a pure metal, the electrons can be thought of as [ Select ] throughout the metal. Using molecular orbital theory, there [ Select ] an energy gap between the filled molecular orbitals and empty molecular orbitals. The [ Select ] orbitals are typically higher in energy and are mostly [ Select ] .
Answer:
Explanation:
In a pure metal, the electrons can be thought of as [concentrated] around atoms throughout the metal. Using molecular orbital theory, there [is ] an energy gap between the filled molecular orbitals and empty molecular orbitals. The [antibonding] orbitals are typically higher in energy and are mostly (filled]
One student measured a spectrum and observed double yellow lines. He claimed that it must be Sodium. Please justify if he is correct. Why
Answer:
We know that the student was measuring a spectrum, and observed double yellow lines, he claimed that it was Sodium.
There are multiple elements with double yellow lines, like Mercury or Sodium, but Sodium has two bright yellow lines, so it is usually identified by them.
So when we look at a spectrum and we see a strong doublet in the yellow range, we can easily assume that it is Sodium.
Here we assume that the student only saw the yellow doublet, this would imply that the yellow doublet is way more intense than the other lines, that can't be seen (while for other elements with double yellow lines, we should see other lines with similar intensity) then we can conclude that it is Sodium.
The student is correct.
Please help meee! Chemistry!
P=18000000/6 zeros. not sure how to do rest
Explanation:
a) [tex]n = \dfrac{PV}{RT} = \dfrac{(1.8×10^7\:\text{Pa})(3\:\text{L})}{(8310\:\text{L•Pa/mol•K})(300\:\text{K})}[/tex]
[tex]\:\:\:\:\:\:\:= 21.7\:\text{mol}[/tex]
b) [tex]P = \dfrac{nRT}{V}[/tex]
[tex]\:\:\:\:\:\:\:\:\:= \dfrac{(50\:\text{mol})(8310\:\text{L•Pa/mol•K})(300\:K)}{(3\:L)}[/tex]
[tex]\:\:\:\:\:\:\:\:\:=4.2×10^7\:\text{Pa}[/tex]
what are the methods used to determine the boiling point of a compound?
Answer:
There are a variety of methods by which a sample's boiling point can be determined, including distillation, reflux, and by using a Thiele tube. The most straightforward method uses a Thiele tube, and has the advantage of using less than 0.5mL of material.
Distillation Method
There are simpler methods than a distillation to measure a compound's boiling point, and it is recommended to explore other options (e.g. Thiele tube) if this is the only goal. However, if materials are limited, or if a purification is planned anyhow, a distillation can be used to determine a compound's boiling point. The distillation technique is discussed in great detail in Chapter 5.
A simple distillation should suffice for most situations and at least 5mL of sample should be used in the distilling flask along with a few boiling stones or stir bar. As the bulk of the material distills, the highest temperature noted on the thermometer corresponds to the boiling point. A major source of error with this method is recording too low a temperature, before hot vapors fully immerse the thermometer bulb. 5 Be sure to monitor the thermometer periodically, especially when the distillation is active. Record the barometric pressure along with the boiling point.
Reflux Method
A reflux setup can also be used to determine a compound's boiling point. Reflux is when a liquid is actively boiling and condensing, with the condensed liquid returning to the original flask. It is analogous to a distillation setup, with the main difference being the vertical placement of the condenser.
Thiele Tube Method
There are a variety of methods by which a sample's boiling point can be determined, including distillation, reflux and by using a Thiele tube. The most straightforward method uses a Thilele tube, and has the advantage of using less than 0.5ml of material.
What molecule is this
Answer:
That is a " ball and stick " model which represents carbon compounds.
Explanation:
This is the answer. Hope it helps you find what you're looking for.
The graph below shows how the temperature and volume of a gas vary when
the number of moles and the pressure of the gas are held constant. How can
the volume of the gas be increased if the pressure is constant?
v
т
A. By increasing the temperature
B. By letting the gas expand over time
C. By letting the gas contract over time
D. By decreasing the temperature
Answer:
D
Explanation:
PV =nRT
So V and T are inversely proportional
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Which of the five type of equilibrium problems best applies to this question: Consider the following reaction at equilibrium. What effect will reducing the volume of the reaction mixture have on the system
Answer:
d
Explanation:
A chemist determines by measurements that 0.0800 moles of bromine liquid participate in a chemical reaction. Calculate the mass of bromine liquid that participates. Round your answer to 3 significant digits.
Answer:
The mass of bromine liquid that participates in a chemical reaction=12.8 g
Explanation:
We are given that
Total number of moles of bromine liquid participate in chemical reaction=0.0800 moles
We have to find the mass of bromine liquid that participates.
Atomic mass of Br=79.9 g
1 mole of bromine liquid=2 atomic mass of bromine (Br)
1 mole of bromine liquid ([tex]Br_2[/tex]) =[tex]2\times 79.9=159.8 g[/tex]
0.0800 moles of bromine liquid=[tex]159.8\times 0.0800[/tex] g
0.0800 moles of bromine liquid=12.784 g
0.0800 moles of bromine liquid[tex]\approx 12.8[/tex] g
Hence, the mass of bromine liquid that participates in a chemical reaction=12.8 g
Consider the synthesis of water as shown in Model 3. A container is filled with 10,0 g of H, and
5.0 g of Oz
Which reactant (hydrogen or oxygen) is the limiting reactant in this case?
Answer:
Oxygen, O₂ is the limiting reactant
Explanation:
We'll begin by writing the balanced equation for the reaction. This is given below:
2H₂ + O₂ —> 2H₂O
Next, we shall determine the masses of H₂ and O₂ that reacted from the balanced equation. This can be obtained as follow:
Molar mass of H₂ = 2 × 1 = 2 g/mol
Mass of H₂ from the balanced equation = 2 × 2 = 4 g
Molar mass of O₂ = 16 × 2 = 32 g/mol
Mass of O₂O from the balanced equation = 1 × 32 = 32 g
SUMMARY:
From the balanced equation above,
4 g of H₂ reacted with 32 g of O₂.
Finally, we shall determine the limiting reactant. This can be obtained as follow:
From the balanced equation above,
4 g of H₂ reacted with 32 g of O₂.
Therefore, 10 g of H₂ will react with
= (10 × 32)/4 = 80 g of O₂.
From the calculations made above, we can see that a higher mass (i.e 80 g) of O₂ than what was given (i.e 5 g) is required to react completely with 10 g of H₂. Therefore, O₂ is the limiting reactant.
Oxygen has been the limiting reactant in the reaction.
A limiting reactant can be defined as the reactant in the reaction in which the product concentration has been dependent.
The balanced equation for the formation of water has been:
[tex]\rm 2\;H_2\;+\;O_2\;\rightarrow\;2\;H_2O[/tex]
For the formation of reaction to form 2 moles of water, 2 moles of hydrogen reacts with 1 mole of oxygen.
The moles can be calculated as:
Moles = [tex]\rm \dfrac{weight}{molecular\;weight}[/tex]
The moles of Hydrogen in 10 g [tex]\rm H_2[/tex]:
Moles = [tex]\rm \dfrac{10}{2}[/tex]
Moles of hydrogen = 5 mol.
Moles of Oxygen in 5 grams Oxygen:
Moles = [tex]\rm \dfrac{5}{32}[/tex]
Moles of oxygen = 0.156 mol.
For the reaction with 2 moles of Hydrogen 1 mole of Oxygen has been required.
For reacting with 5 mol of Hydrogen, moles of oxygen required are:
Moles of oxygen = [tex]\rm \dfrac{1}{2}\;\times\;5[/tex]
Moles of oxygen required = 2.5 moles.
The available oxygen = 0.156 moles.
Since the moles of oxygen available is lesser than required, the formation of the product has been dependent on the concentration of the oxygen.
Thus, oxygen has been the limiting reactant in the reaction.
For more information about the limiting reactant, refer to the link:
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what is the machine used to check melting point called?
Answer:
Melting-point apparatus
The element least likely to obey the octet rule in forming chemical bonds is Group of answer choices oxygen. carbon. nitrogen. neon. fluorine.
Answer:
neon
Explanation:
The octet rule states that atoms of elements are stable when they possess 8 electrons on their outermost shell.
Hence, atoms of elements participate in chemical reactions in order to attain this octet structure (eight electrons in the outermost shell).
Neon is a noble gas and already has eight electrons in its outermost shell. Hence, neon is least likely to obey the octet rule.
what is sterilization
Answer:
Sterilization refers to any process that removes, kills, or deactivates all forms of life and other biological agents like prions present in a specific surface, object or fluid, for example food or biological culture media.
How many molecules make up 12.8g of N2O4
Answer:
8.35 × 10 ²² molecules
Explanation:
gram molecular weight of N2O4
= 2 × 14 + 4 × 16
= 28 + 64
= 92g
1 mole N2O4 has 6 × 10²³ molecules of N2O4 and weighs 92g
therfore,
92 g has = 6 × 10²³ molecules
12.8 g has =
[tex] \frac{6 \times 10 {}^{23}}{92} \times 12.8[/tex]
= 0.835 × 10²³
= 8.35 × 10 ²² molecules
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33.5 cs=_________s
Answer: 3.4 × 10 -1 equal 33.5 cs. May I have brainiest? pls. (the -1 is to the power of the ten.
If 11g of a gas occupies 5.6dm'3at s.t.p., calculate it's vapour density (1.0mol of a gas occupies 22.4dm'3at s.t.p.).
Answer:
[tex]{ \boxed{ \bf{vapour \: density = 2 \times molecular \: mass}}} \\{ \tt{ PV= (\frac{m}{ m_{r}}) RT}} \\ { \tt{3 \times 5.6 = \frac{11}{m _{r}} \times 0.0831 \times 273}} \\ { \tt{m _{r} = 14.85 \: g}} \\ \\ { \bf{vapour \: density = 2 \times m _{r}}} \\ = 2 \times 14.85 \\ = 29.7 \: { \tt{g {dm}^{ - 3} }}[/tex]
Which is used to measure conc. HCl for preparation of 0.1M HCl solution?
a. Volumetric flask c. Measuring cylinder
b. Pipette d. Wash bottle
Answer:
option a
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Which compound contains both sigma and pi bonds... HCCl3, H2CO, H2S, or HBr?
Answer:
H2CO
Explanation:
Becuase it has 2 sigma bonds plus one pi bond and one sigma bond that consitute the double bond between C and O.
Answer:
B. H2CO
Explanation:
Draw the Lewis structure for the polyatomic formate anion. Be sure to include all resonance structures that satisfy the octet rule.
Answer:
Lewis structure of polyatomic formate anion.
Explanation:
To draw Lewis structure for any chemical species,
1)Count the total number of valence electrons present in it.
This can be obtained by adding valence electrons of each constituent atom.
2)Arrange those valence electrons in such a way that each atom should attain eight electrons around it to satisfy octet theory.
The structure of formate ion and its Lewis structure are shown below:
HCOO- is the formate ion.
It has total:
1+4+6+6+1 = 18 valence electrons.
Since, hydrogen has one, carbon has four and oxygen has six valence electrons and the charge of the anion is one.
Arrange this 18 electrons in such a way that each atom should get 8 electrons around it.
Resonance structures of formate ion:
Me please answer as follows
Answer:
no reaction occurs .that is no product
how to separate and purify the Flufenamic acid from the aqueous layer
Answer:
Explanation:
H