Answer:
The composition of air can be determined by an experiment which includes passing a known volume of air, measured at a known temperature and pressure, over sufficient amount heated copper granules/powder, and measuring the volume gas remaining after the gas cools down to the temperature at which the first measurement was taken
Oxygen reacts with copper according to the following chemical reaction
2Cu (s) + O₂ (g) → 2CuO (s)
Cupper does not react with the other constituents of air
Whereby the initial volume of air was 100 cm³, we have;
Percentage of oxygen in air = 100 - The final volume reading of the container initially holding the air
When done using am appropriate experimental setup, the percentage of gases remaining equals 79% to 80%, therefore, the percentage composition of oxygen in air is between 20 and 21 percent
Explanation:
True or false, The four units that must always be used when using the ideal gas are 44.0 liters
Answer:
for volume only liters can be used
Explanation:
Which of the following is true of science? (2 points)
It can be disproven by philosophy and religion.
It does not change after new evidence is discovered.
It is based on the personal opinions of scientists.
It is based on testable and replicable evidence.
Answer:
It is based on testable and replicable evidence.
A sample of gas has a volume of 20 cm³.The pressure is changed to 90 kPa at constant temperature,while the volume increases to 75 cm³.What was the original pressure of the gas?
Answer:
337.5kPa ~ 338kPa
Explanation:
Using the ideal gas law PV=nRT we have the following definitions from the problem:
V(initial) = 20cm³
P(initial) = ?kPa
V(final) = 75cm³
P(final) = 90kPa
Since we know that the number of moles of the sample did not change, nor did the temperature, nor does the ideal gas constant (R) we can rewrite this equation to state:
P(initial)V(initial) = nRT =P(final)V(final) ~ P(initial)V(initial) = P(final)V(final)
Rearranging this equation as we are solving for the initial pressure we find that:
P(initial) = (P(final)V(final))/V(initial)
P(initial) = ((90kPa)(75cm³))/20cm³
P(initial) = 337.5kPa ~ 338kPA
write an importance of endothermic reactions
Answer:
the uses of exothermic reactions are:
1) lighting of stove
2) self heating cans
3) hand warmers
4) in some case exothermic process can be used to cook food such as rice (by adding calcium oxide to water heat is evolved and it helps to cook food )
Explanation:
hope this helps you pls mark me as brainilst
1.Which of the following forms only Ionic Bond?
1)Ca 2)C 3)Si 4)P
2.How many atoms of Na are present in 92 a.m.u of it?
a)4 b)5 c)6 d)7
The Answer is A)4 atoms of NA are present in 92 a.m.u
The boiling point of water is 100ºC. The boiling point of acetone is 56ºC. Which statement about distilling a mixture of acetone and water is correct?
Acetone remains in the original container.
Water will vaporize from the mixture before acetone.
Acetone is captured and cooled.
Water is collected as it leaves the mixture.
Answer:
Acetone is captured and cooled.
Explanation:
The boiling point of acetone is lower than that of water, so it will vaporise before water. Then acetone will be captured and cooled to separate it from its mixture with water.
The statement which is correct about distilling a mixture of acetone and water is as follows:
Acetone is captured and cooled.Thus, the correct option is C.
What is Distillation?Distillation may be defined as a procedure that generally involves the conversion of a liquid into a vapor that is eventually condensed back to liquid form. With the help of this process, the separation of components or substances from a liquid mixture by using selective boiling and condensation occurs.
Acetone has the lowest boiling point as compared to water. So, it boils faster than that water and vaporizes before water. After the termination of this process, the acetone will be predominantly captured and cooled to separate it from its mixture with water.
Therefore, the correct option for this question is C.
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If 16.4 grams of calcium nitrate is heated as shown in the reaction:
2Ca(NO3)2 -> 2CaO + 4NO2 + O2.
Calculate the volume of nitrogen dioxide produced at STP.
Answer:
7.2
Explanation:
you first have to find the number of moles of nitrogen dioxide by using the number of moles for calcium nitrate and the mole to mole ratios
number of moles of calcium nitrate=mass/mm
=16.4/102
=0.16g/mol
then you use the mole to mole ratios
2 : 4
0.16: x
2x/2=0.64/2
x=0.32g/moles of nitrogen dioxide
then you use the formula for the volume
v=22.4n
=22.4×0.32
=7.2
I hope this helps
write any two conditions at which a body of certain mass weightless
Answer:
A body becomes weightless in a zero-gravity scenario and when a force is applied to a body that is equal and opposite to the force of gravity. If the body is falling only under the influence of gravity.
Answer:
A body becomes weightless in a zero-gravity scenario and when a force is applied to a body that is equal and opposite to the force of gravity.If the body is falling only under the influence of gravity.
difference between Nitrogen 1 oxide and Oxygen
Answer:
one atom of oxygen is not equal to oxygen
Convert 48,987 minutes to years
using the method of dimensional analysis
Answer:
Explanation:
48000 minutes [ 1 hour / 60 min ] 1 day / 24 hours ] [365 days / year]
48000 * [ 1/(60 * 24 * 365)]
48000 * [1 / 525600]
There are 0.0930954years in 48000 minutes
the text of oxygen gas in the laboratory
Explanation:in testing for oxygen a glowing splint is used.
the glowing splint is brought in the presence of the test tube containing the gas
the glowing splint rekindles or lights up showing that oxygen is present.
this is a positive test because oxygen supports burning or combustion
Which equation describes a physical change? i. H2O(s) ⟶ H2O(l) ii. Na+(aq)+Cl−(aq) +Ag+(aq)+NO3−(aq) ⟶ AgCl(s)+Na+(aq)+NO3−(aq) iii. CH3OH(g)+O2(g) ⟶ CO2(g)+H2O(g) iv. 2H2O(l) ⟶ 2H2(g)+O2(g) v. H+(aq)+OH−(aq)⟶ H2O(l)
Answer:
The answer is "Option i"
Explanation:
In this question, only option (i) is correct, and others were wrong which can be defined as follows:
In option (ii):
[tex]Na^+\ (aq)+Cl^- \ (aq) +Ag^+ \ (aq)+NO_3^- \ (aq) \to AgCl\ (s)+Na^+ \ (aq)+NO_3^-\ (aq) \\\\[/tex]
It is the complete ionic equation.
In option (iii):
[tex]CH_3OH\ (g)+O_2\ (g) \to CO_2\ (g)+H_2O\ (g)[/tex]
It is the combustion reaction but a not balanced equation.
In option (iv):
[tex]2H_2O\ (l) \to 2H_2\ (g)+O_2\ (g)[/tex]
It is the decomposition equation.
In option (v):
[tex]H^+\ (aq) +OH^-\ (aq)\to H_2O\ (l)[/tex]
It is the complete ionic equation.
Describe the principle and process for the manufractured of sulphuric acid witha a well labeled diagram by contact process.
The steps involved in the manufacture of sulphuric acid by contact process:
(1) Sulphur (or iron pyrites) are burnt in air to form sulphur dioxide.
S+O2→SO24FeS2+11O2→2Fe2O3+8SO2
(2) Catalytic oxidation of sulphur dioxide to sulphur trioxide.
2SO2+O2V2O52SO3ΔrHo=−196.6kJ
The reaction is reversible and exothermic.
(3) Sulphur trioxide is dissolved in 98% sulphuric acid to form oleum (fuming sulphuric acid).
SO3+H2SO4→H2S2O7
(4) Oleum is diluted with water to form sulphuric acid of desired concentration.
H2S2O7+H2O→2H2SO4
and
Manufacture of H2SO4 by contact process involves three steps:
1. Burning of sulphur in air to generate SO2.
2. Conversion of SO2 to SO3 by oxidation with air in the presence of
Which of the following is a common property of both strong acid and strong base?
a. They are good electrolytes
b. They are non-electrolytes
c. They are weak electrolytes
d. They are sour in test
Answer:
They are good electrolytes
Which sentence describes existing cells?
All cells, once formed, continue to live forever.
All cells come from previously existing cells.
All the cells that are on Earth have always been here.
All cells develop from the remains of other cells.
Which of the following molecules contains six bonding electrons?
A C2H4
B CO2
C H2S
D NCl3
Answer:
c2h4 (etthane........
bexcuse it has 6 bond of hydrogen
C₂H₄ molecules contains six bonding electrons. Therefore, option A is correct.
What do you mean by the term bonding ?Chemical bonding is the process through which two or more atoms, molecules, or ions establish a chemical link to create a chemical compound. The atoms in the resultant molecule are held together by these chemical bonds.
Chemical bonds have three basic characteristics that must be taken into account: their strength, length, and polarity. The distribution of electrical charge among the atoms connected by a bond determines its polarity.
C₂H₄ molecules has six bonding electrons. This molecule is called as Ethylene. When bonding is done between two atoms, each atom shares a pair of electrons with each other.
Hence, for every one bond, two electrons are shared between two atoms
Thus, option A is correct.
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7. What measures are applicable in the context of Nepal to push energy crisis further. Describe any three points clearly.
Answer:
which energy?........
Explanation:
..........................
........
....
Please help I have been stuck on this problem for a couple hours and can't figure it out
Answer:
11.92 Liters O₂(g) at STP
Explanation:
For most stoichiometry problems, if one will convert all given data into moles, solve by rxn ratios, then finish by converting to needed dimensions to complete problem.
2Pb(NO₃)₂ => 2PbO + 4NO₂ + O₂
Given 237.5 grams PbO formed in reaction = 237.5 g/223.2 g/mole = 1.064 mole PbO
From equation ratios, moles O₂ formed = 1/2(moles PbO) = 1/2(1.064 moles O₂) = 0.532 mole O₂
0.532 mole O₂ = 0.532 mole x 22.4 liters/mole at STP = 11.91756272 liters (calculator answer) ≅ 11.92 liters O₂ at STP (4 sig.figs. based on given 237.5g PbO)
what apparatus is used to investigate the conductivity of solutions
The world is made up of
Answer:
Explanation:
The world is made up of living beings .
help me please I will mark as brainliest for the first correct answer
Answer:
1. 3-methylpentane
2. 2-bromo-3-chloropentane
3. 2,2,4-trimethylpentane
Explanation:
1. CH3CH2CH(CH3)CH2CH3.
Methyl group is in the third carbon atom in the long chain. The organic compound has five(5) carbon atoms thus it is named as pentane.
Therefore the name of the compound is
3-methylpentane
2. CH3CH(Br)CH(Cl)CH2CH3
The compound has Chlorine and Bromine in the carbon chain. Chlorine is given as chloro-, Bromine is given as bromo, depending on the position in the carbon chain. Bromine is located in 2 carbon atom and chlorine is in third(3) carbon atom in the long chain. The long chain has five carbon atoms thus pentane.
Naming of the compound we begin with the on lowest in the alphabet. The name of the organic compound is therefore;
2-bromo-3-chloropentane
3. CH3CH(CH3)3CH(CH3)CH2CH3
In this long chained organic compound, methyl-group is found in 2,2 and 4th positions. Since this is still pentane, naming the organic compounds, we start with the one with the lowest carbon. Therefore this becomes;
2,2,4-trimethylpentane
I hope this helps you to know how to name the organic compounds.
How much water will the measuring cup have if you poured 1/2 of it out?
Please help with the Volume one
Answer:
im a just achild
Explanation:
Answer:
c
Explanation:
0.5dm³
follow me if you want
Is water the only liquid? If not, name 5 more
Answer:
Is water the only liquid? If not, name 5 more
Water, ethanol, household bleach, blood, paint, milk, gasoline, mineral oil, acetone and butyl alcohol are examples of liquids. Liquids' properties allow them to flow or be poured easily into containers, lava
water is not the only liquid.
Answer:
apple juice, milk, smoothie, blood, urine
Can you help me on this. I will support your correct answer
what is a cubic unit cell ?
cubic unit cell is the smallest repeated unit which have all angles equal to 90 and all have edge lengths equal
It is the type of the Unit cell which is having all angles equal to 90 and all sides equal to each other
it's is a unit cell with cubic structure
If ya could change somethin bout ya previous science classes what would it be?
If I could change something in my previous science classes, it would have been the fact that I struggled in the question concerning exponents. It was simple one, but I don't know how I didn't understood that. For example, if there is a question with a calculation "xy²", then I would first multiply x and y, and then calculate the exponent. I did 3 of the questions wrong because of this, it was when I was in 7th grade. I wish I had not done this kind of silly mistake. I an in 10th grade and understand it well now, though.
What is the pressure in atm exerted by 1.8 g of H2 gas exert in a 4.3 L balloon at 27ºC? R = 0.821(L*atm) / (mol*K)
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The pressure in atm exerted by 1.8 g of H₂ gas exert in a 4.3 L balloon at 27ºC is 5.12 atm
What is Ideal gas law ?The ideal gas law (PV = nRT) relates the macroscopic properties of ideal gases. An ideal gas is a gas in which the particles (a) do not attract or repel one another and (b) take up no space (have no volume).
Let's convert grams to moles (via molar mass).
Molar Mass (H₂) : 2 (1.008 g/mol)
Molar Mass (H₂) : 2.016 g/mol
1.8 grams H₂ 1 mole
---------------------- x ---------------------- = 0.893 moles H₂
2.016 grams
The Ideal Gas Law equation looks like this:
PV = nRT
In this equation,
P = pressure (atm) V = volume (L) n = moles R = Ideal Gas Constant (0.0821 L*atm/mol*K)T = temperature (K)After converting Celsius to Kelvin, you can put the given values into the equation and simplify to find the pressure.
P = ? atm R = 0.0821 L*atm/mol*K
V = 4.3 L T = 27 °C + 273.15 = 300.15 K
n = 0.893 moles
PV = nRT
P (4.3 L) = (0.893 moles) (0.0821 L*atm/mol*K)( 300.15 K)
P (4.3 L) = 22.0021
P = 5.12 atm
Therefore, The pressure in atm exerted by 1.8 g of H₂ gas exert in a 4.3 L balloon at 27ºC is 5.12 atm
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Cho các dung dịch: Glucozơ, glixerol, fomanđehit, etanol. Có thể dùng thuốc thử nào sau đây để phân biệt được cả 4 dung dịch trên?
A. Cu(OH)2; B. Dung dịch AgNO3 trong NH3;
C. Na kim loại; D. Nước brom.
Xem thêm tại: https://loigiaihay.com/bai-2-trang-25-sgk-hoa-hoc-12-c55a8069.html#ixzz71KH6guhm
Answer:
chắc là câu B í
Explanation:
Which among the following mixtures will show tyndal effect?
i) copper sulphate solution
ii) sand in water.
iii) milk.
iv) starch solution
Answer:
milk and starch solution are the colloids, hence these will show the tyndall effect
Answer:
milk and starch solution
Explanation:
Tyndall effect is shown by colloidal solutions. It is not shown by true solutions or suspensions.
Milk and starch solution are colloidal solutions. They show tyndall effect. On the other hand, common salt and copper sulphate solution are true solutions. They do not show tyndall effect.
