Give 3 examples of chemical change and physical change in daily life
Explanation:
Physical change
★ Boiling of water
❤︎ freezing of water
❣︎ washing of clothes
♫︎ mixing black and brown stones
Chemical change
➪ making of dough
㋛︎ burning of wood
❥︎ cooking of the raw food
❁ burning of paper
ꨄ︎ rusting of iron
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how many moles of oxygen atoms are present in 0.4 moles of oxygen gas
Answer:
Each molecule of O2 is made up of 2 oxygen atoms. So 1 mole of O2 molecules is made up of 2 moles of oxygen atoms. Therefore 1 mole of oxygen gas contains 2 moles of oxygen atoms. And 0.4 moles of oxygen gas contains 0.8 moles of oxygen atoms.
There are 0.8 moles of oxygen atoms in 0.4 moles of oxygen gas.
Oxygen gas (O₂) consists of two oxygen atoms bonded together. Therefore, to determine the number of moles of oxygen atoms present in a given amount of oxygen gas, we can simply multiply the number of moles of oxygen gas by the number of oxygen atoms per molecule, which is 2.
Given that we have 0.4 moles of oxygen gas, we can calculate the number of moles of oxygen atoms as follows:
Number of moles of oxygen atoms = Number of moles of oxygen gas × Number of oxygen atoms per molecule
= 0.4 moles × 2
= 0.8 moles
Therefore, there are 0.8 moles of oxygen atoms present in 0.4 moles of oxygen gas.
This calculation is based on the stoichiometry of oxygen gas, which indicates that each molecule of O₂ contains two oxygen atoms. By considering the mole ratio between oxygen gas and oxygen atoms, we can determine the number of moles of oxygen atoms in a given quantity of oxygen gas.
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Which chemical can remove color of red/Pink phenol and make it clear like water transparent?
What information does the first quantum number of an electron give?
A. The sublevel that the electron is in
B. The specific orbital the electron is in
C. The energy level the electron is in
D. The spin that the specific electron has
Answer:
с
Explanation:
the first quantum number of an electron gives the information about the energy level the electron is in
The information first quantum number of an electron give is the energy level the electron is in.
What are quantum numbers?Quantum numbers is a set of symbols which gives idea about the position of electron present inside an atom.
First quantum number is denoted by symbol 'n' which gives idea about the number of shell or energy level in which electron is present.The sublevel that the electron is in is the second quantum number denoted by symbol 'l'.The specific orbital in which electron is present is denoted by symbol 'm' and it is the third quantum number.The spin that the specific electron has is the forth quantum number and denoted by symbol 's'.Hence first quantum number of electron gives ideal about the energy level.
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calcium is added to water,the liberated gas is
Answer:
In both cases, the gas evolved is H2. When calcium reacts with water the heat evolved is not suffcient for hydrogen to catch fire. On the other hand, sodium metal reacts with water violently and in this case a lot of heat is evolved which is sufficient for hydrogen to catch fire.
Explanation:
may this answer is helpful for you
Hydrogen
The reaction is given by
[tex]\boxed{\sf {Ca\atop Calcium}+{H_2O\atop Water}\longrightarrow {Ca(OH)_2\atop Calcium\:Hydroxide}+{H_2\atop Hydrogen}}[/tex]
Balanced equation:-
[tex]\boxed{\sf {Ca\atop Calcium}+{2H_2O\atop Water}\longrightarrow {Ca(OH)_2\atop Calcium\:Hydroxide}+{H_2\atop Hydrogen}}[/tex]
A skydiver slows down from 65 m/s to 5 m/s by opening the parachute. If this
takes 0.75 seconds, what is the skydiver's acceleration?
A. 45 m/s2 up
B. 80 m/s2 up
C. 45 m/s2 down
D. 80 m/s2 down
Answer:
D. -80m/s^2
Explanation:
V = u + at
5 = 65 + a (0.75)
0.75a = -60
a = -60/0.75
a = -80m/s^2
Therefore, is decelerating at 80m/s^2
Answer:
[tex]\boxed {\boxed {\sf D. \ 80 \ m/s^2 \ down}}[/tex]
Explanation:
We are asked to find the acceleration of a skydiver. Acceleration is the change in velocity over the change in time, so the formula for calculating acceleration is:
[tex]a= \frac{v_f-v_i}{t}[/tex]
The skydiver was initially traveling 65 meters per second, then he slowed down to a final velocity of 5 meters per second. He slowed down in 0.75 seconds.
[tex]\bullet \ v_f = 5 \ m/s \\\bullet \ v_i= 65 \ m/s \\\bullet \ t= 0.75 \ s[/tex]
Substitute the values into the formula.
[tex]a= \frac{ 5 \ m/s - 65 \ m/s}{0.75 \ s}[/tex]
Solve the numerator.
[tex]a= \frac{-60 \ m/s}{0.75 \ s}[/tex]
Divide.
[tex]a= -80 \ m/s^2[/tex]
The acceleration of the skydiver is -80 meters per second squared or 80 meters per second squared down. The skydiver is slowing down or decelerating, so the acceleration is negative or down.
ANSWER THESE QUESTIONS PLEASE
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Answer:
By definition, a pure substance or a homogeneous mixture consists of a single phase. A heterogeneous mixture consists of two or more phases. When oil and water are combined, they do not mix evenly, but instead form two separate layers.
Explanation:
Sorry only knew the answer to the first question
Answer:
To make a saturated solution, 36 gm of sodium chloride is dissolved in 100 gm of water at 293 K. Find its concentration at this temperature.
Mass per cent is a way of expressing a concentration or describing the component in a particular mixture. The solution composition can be expressed in mass percentage that depicts the mass of solute present in a given mass of solution.
The quantity of solute is expressed in mass or by moles. For a solution, the mass per cent is described as the grams of solute per grams of solution, multiplied by 100 to get the percentage.
Concentration
Mass of sodium chloride (Solute) = 36gm
Mass of water (solvent) = 100 gm
Mass of solution = 36+100
∴ Mass of solution = 136 gm
Concentration = (Mass of Solute / Mass of Solution) * 100
Concentration = (36/136) × 100
Concentration = 26.47%
Temperature
If temperature increases, solubility increases and if temperature decreases, solubility decreases.
It is possible to distinguish the particles of solute from those of solvent in a suspension, since particle size is bigger in suspensions, hence it is easier to distinguish the particles of solute.
Explanation:
1.46 mol sample of nitrogen gas at a temperature of 14.0 °C is found to occupy a volume of 23.7 liters. The pressure of this gas sample is mm Hg
Explanation:
Since there are no gas constant with the unit of mmHg, you just have to use the gas constant for atm, and then convert that into mmHg
Which substance has the highest boiling point?
Select the correct answer below:
A) ethyl ether
B) ethyl alcohol
C) water
D) these all have the same boiling point
Answer:
D) these all have the same boiling point
Please guys please answer this
Answer:
1. Because the rules will keep you safe it prevents you from getting hurt.
2.i) don't taste chemical
ii) Always wear protective gears
iii) be careful with tool
iv) wear protective gloves
Explanation:
help everyone get out quickly
Calculate [H3O+] for pH 1.86. Steps please.
Answer:
[H₃O⁺] = [H⁺] = 10^-pH = 10⁻¹°⁸⁶ = 0.0138M in [H⁺]
Explanation:
By definition pH = -log[H⁺] => [H⁺] = 10^-pH = 10⁻¹°⁸⁶ = 0.0138M in [H⁺]
Using your calculator ... I am using a TI-30XA scientific calculator.
=> start by entering the number 1.86 => then press the (+/-) function => this will insert a negative symbol => -1.86,=> next find button with "2nd" printed on face (on some calculators the button is in yellow); press this button to change to 'secondary mode',=> find the symbol (10ˣ) ... the button below this symbol is usually the 'log' button, then press it => the answer of interest will show in the display window. => ...Depending on the calculator, the answer may show as 0.0138, or 1.38x10⁻², or 1.38E-2 (=1.38 x 10⁻²). It is the user's job to insert dimensional units into answer of interest => 0.0138M, or 1.38 x 10⁻²M, or 1.38E-2M.
1.38E-2 which is 1.38 x 10⁻².
Assume you have 4 solids (A, B, C and D) of similar mass. Which of these requires the greatest energy input to melt?
polar covalent
covalent network
ionic compound
nonpolar covalent
The solid that require the greatest energy input to melt by mass is the option;
Covalent network
Reason for the above answer is as follows;
The elementary particles of a solid are held together by bonds that require
an input of energy to unlock, and once broken, the particles are then able
to change location within their containing vessels with less restrictions
Types of bonds
Polar covalent molecular solids have the following characteristics;a) Soluble in water b) Low melting point, b) Conduct electricity
Solids that are made up of a covalent network have the following characteristicsa) High melting point temperature b) Non conductive of electricity c) Not soluble in water
Solids of ionic compounds have the following characteristics;a) High melting point temperature b) The liquid state and solution
conducts electricity c) Soluble in water
Solids that have nonpolar covalent bonds have;a) Low melting point b) Normally in the gaseous or liquid state b) Not water soluble
Therefore, the covalent network, and the solids ionic compounds require the most energy to melt, however, the strength of the ionic bond in an ionic compound is a factor the charges present and the sizes of the atom, while
the covalent network solid, are combined to form essentially as a single
molecule and therefore require the greatest heat energy input break the bonds of the molecule down in order to melt
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A filament for a light bulb needs to conduct electricity. Which of the elements listed below might be useful as a light bulb filament? Explain your thinking.
A. Tungsten, W
B. Sulfur, S
C. Bromine, Br
Answer:
A. tungsten
Explanation:
Tungsten is a material which high melting point ie. does not melt easily incase of high temperature
Answer:
option(A):Tungsten
Explanation:
tungsten has highest melting point.
Why benzene is called aromatic compound according to Huckel’s rule?
Answer:
It obeys rule
Explanation:
Benzene is an aromatic hydrocarbon because it obeys Hückel's rule.
Answer:
Benzene is an aromatic compound because it is planar, cyclic, conjugated and has (4n +2) π electrons, where n= 1.
Explanation:
Hückel's rule states that a molecule is aromatic if it is planar, cyclic, conjugated and has (4n +2) π electrons.
Breaking it down into 4 requirements, we have:
planarcyclicconjugated(4n +2) π electronsLet's look at each of the 4 parts!
What is planar?
Planar refers to the molecule being flat. When an atom is sp² hybridized, it is in a trigonal planar geometry. Let's look at the benzene molecule. Each carbon is attached to 3 other atoms, namely 2 carbons and 1 hydrogen. This means that each carbon is sp² hybridized, making the molecule planar.
Cyclic
This refers to the molecule having a closed ring shape. Benzene fulfils this criteria.
Conjugation
This refers to a system of connected p orbitals, which allows π electrons to delocalize. Each carbon atom in benzene has one 2p orbital, making benzene a conjugated molecule. For molecules that are not cations or anions, conjugated molecules are those that have alternating single and double bonds.
(4n +2) π electrons
n is an integer (e.g. 0, 1, 2, 3) thus for the molecule to be aromatic, it can have 2, 6 or 10 π electrons (non exhaustive). This separates an aromatic compound from an antiaromatic compound, which has 4n π electrons instead.
Benzene has 6 π electrons, so n has a value of 1 in this case.
Thus, benzene is an aromatic compound because it is planar, cyclic, conjugated and has (4n +2) π electrons.
_______
Counting the number of π electrons
Let's look at π bonds!
A double bond is made up of 1 σ bond and 1 π bond, and each π bond is made up of 2 π electrons. We do not count the number of single bonds since single bonds are made up of 1 σ bond only.
There are 3 double bonds in the Kekulé structure of benzene. Thus, the number of π electrons in benzene is 3(2)= 6.
Attached diagrams
Kekulé structure of benzenesp² hybridized carbon6 p orbitals in benzene ringIdentify the conjugate pairs in the following acid-base reaction
H₂CO₃(aq) + C₅H₅N(aq) HNO₃-(aq) + HC₅H₅N+(aq)
H2CO3 is an acid because it gave away a proton to become HNO3~.
HNO3~ is a conjugate Base because Acids become conjugate Bases after giving away a proton.
C5H5N is a base because it accepted the proton from H2CO3 to become HC5H5N+.
HC5H5N+ is a conjugate Acid because Bases become Conjugate Acids after accepting a proton.
What volume of carbon dioxide is required for inflating the Ziploc bag prototype ?
Answer:
The front passenger airbag has a volume of around 140 l and fully inflates in around 35 ms. The process is similar for side airbags (thorax airbags).
Which method of separation would be most appropriate for separating a mixture of water and alcohol?
A. evaporation
B. chromatography
C. distillation
D. filtration
Answer:C. distillation
Explanation:
Compounds having different boiling points when mixed can be separated by Fractional distillation.
Now when there is a mixture of water and alcohol, Upon heat, we would see that the alcohol will boil at a lower temperature than water for eg, ethanol will boil at 78.5 degrees Celsius, vaporizes and distills into the fractionating columns leaving the water which we know boils at 100 degrees Celsius.
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Cho biết độ tan của NH4Cl trong nước ở 20oC và 70oC lần lượt là 37,2 g/100 gam nước và 60,2 gam/100 g nước. Hòa tan 166,8 gam NH4Cl vào 400 gam nước ở 70oC thu được dung dịch X. Sau đó, hạ nhiệt độ dung dịch X xuống 20oC. Tính khối lượng (gam) NH4Cl kết tinh lại trong X?
Answer: Hợp chất CTHH 0 °C 10 °C 20 °C 30 °C 40 °C 50 °C 70 °C
Actini(III) hydroxide Ac(OH)3 0,0022
Amonia NH3 1176 900 702 565 428 333 188
Amoni azua NH4N3 16 25,3 37,1
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hehe
7.7 cm
9.8 cm
0.00
0.162 m
Answer:
Volume = 1222.5cm³
Explanation:
If the question is about the volume of the rectangle:
The volume of a rectangle is obtained by the multiplication of its 3 dimensions: Length, width, height.
In the problem, the length of the rectangle is 0.162m = 16.2cm
The width is 7.7cm
And the height is 9.8cm
The volume is:
Volume = 16.2cm*7.7cm*9.8cm
Volume = 1222.5cm³Predict the missing component in the nuclear equation.
238 92U → 234 90Th + X
A. 4 2He
B. 0 -1e
C. 0 0v
Answer:
A
Explanation:
helium (alpha particle)
Predict the reactants of this chemical reaction. That is, fill in the left side of the chemical equation. Be sure the equation you submit is balanced. (You can edit both sides of the equation to balance it, if you need to.)
Note: you are writing the molecular, and not the net ionic equation.
NaClO3(aq) + H2O(l)
Answer:
HClO₃(aq) + NaOH(aq) ⇒ NaClO₃(aq) + H₂O(l)
Explanation:
We have the products of a reaction and we have to predict the reactants. Since the products are salt and water, this must be a neutralization reaction. In a neutralization reaction, an acid reacts with a base. To form NaClO₃, the acid must be HClO₃(aq) and the base NaOH(aq). The balanced chemical equation is:
HClO₃(aq) + NaOH(aq) ⇒ NaClO₃(aq) + H₂O(l)
explain chlorination of methane
Answer:
Methane and chlorine
If a mixture of methane and chlorine is exposed to a flame, it explodes - producing carbon and hydrogen chloride. This is not a very useful reaction! The reaction we are going to explore is a more gentle one between methane and chlorine in the presence of ultraviolet light - typically sunlight. This is a good example of a photochemical reaction - a reaction brought about by light.
CH4+Cl2+energy→CH3Cl+HCl(3.4.2)
The organic product is chloromethane. One of the hydrogen atoms in the methane has been replaced by a chlorine atom, so this is a substitution reaction. However, the reaction doesn't stop there, and all the hydrogens in the methane can in turn be replaced by chlorine atoms.
Substitution reactions happen in which hydrogen atoms in the methane are replaced one at a time by chlorine atoms. You end up with a mixture of chloromethane, dichloromethane, trichloromethane and tetrachloromethane.
I hope this help you!:)
Explanation:
Aspirin that has been stored for a long time may give a vinegar like odour and give a purple colour with FeCl3. What reaction would cause this to happen
?.
Answer:
See explanation
Explanation:
The IUPAC name of aspirin is 2-Acetoxybenzoic acid. It is composed of an acetoxy moiety and a benzoic acid moiety.
The compound can be hydrolysed under prolonged storage conditions to yield acetic acid which causes the vinegar like odour.
Also, one of the products of this hydrolysis bears a phenol group which reacts with FeCl3 to give a purple color.
5 points ) Which of the following is a benefit of using email to communicate at work ? a) You can express yourself in a limited number of characters b) You don't have to worry about using proper grammar. c) You always get a response right away. d ) You can reach a large audience with one communication .
Answer:
C
Explanation:
How many grams of Al were reacted with excess HCl if 3.86 L of hydrogen gas were collected at STP in the following reaction?
2 Al (s) + 6 HCl (aq) → 2 AlCl₃ (aq) + 3 H₂ (g)
The amount, in grams, of Al that reacted with excess HCl if 3.86 L of hydrogen gas were collected at STP in the reaction would be 3.099 grams.
Stoichiometric problemFrom the equation of the reaction, the mole ratio of Al that reacts with that of hydrogen gas that forms is 2:3.
At STP, 1 mole of any gas is equivalent to 22.4 Liters of the gas.
But only 3.86 L of hydrogen was formed in the reaction.
The equivalent mole of 3.86 L hydrogen at STP would be:
3.86 x 1/22.4 = 0.1723 moles
From the mole ratio, the equivalent mole of Al that will produce 0.1723 moles of hydrogen gas would be:
0.1723 x 2/3 = 0.1149 moles
Recall that: mass = mole x molar mass
Mass of 0.1149 moles Al = 0.1149 x 26.98
= 3.099 grams
Thus, the amount of Al that reacted with excess HCl is 3.099 grams.
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A strawberry nutritional drink used for a liquid diet is flavored with methyl butanoate. Draw the structure of methyl butanoate.
Answer:
See explanation and image attached
Explanation:
Methyl butanoate is an ester. Esters have the general molecular formula, RCOOR where the two Rs may represent the same or different alkyl groups.
Methyl butanoate is has a fruity odor, smelling like apples or pineapples fragrance. It is also called methyl butyrate.
The structure of the compound is shown in the image attached to this answer.
Which of the following chemical equations depicts a balanced ionic equation?
A. 2OH−+Ca2+−>Ca(OH)2
B. OH−+Ca2+−>Ca(OH)2
C. 2OH−+Ca2+−>2Ca(OH)2
D. OH−+2Ca2+−>Ca(OH)2
Answer:
[tex]{ \sf{A. \: 2OH {}^{ - } _{(aq)} +Ca {}^{2 + } _{(aq)} −>Ca(OH) _{2(s)} }}[/tex]
The chemical equations depict a balanced ionic equation is 2OH−+Ca2+−>Ca(OH)2. option A is correct.
What is the ionic equation?
An ionic equation is a chemical equation in which the electrolytes in an aqueous solution are expressed as dissociated ions. The ions in aqueous solutions are stabilized by ion-dipole interactions with water molecules
Strong acids, strong bases, and soluble ionic compounds (usual salts) exist as dissociated ions in an aqueous solution, and Weak acids and bases and insoluble salts are usually written using their molecular formulas because only a small amount of them dissociates into ions.
Ag+(aq) + NO3-(aq) + Na+(aq) + Cl-(aq) → AgCl(s) + Na+(aq) + NO3-(aq) is an ionic equation example.
Therefore, the balanced ionic reaction will be 2OH−+Ca2+−>Ca(OH)2. option A is correct.
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What is the formula for tin (II) chlorate decahydrate?
Answer:
The formula is:
Sn(ClO3)2
Tin(II) Chlorate is also called stannous chlorate and is a white-colored solid. Hydrates are the addition of water molecules. Tin (II) chlorate decahydrate is represented by Sn(ClO₃)₂ . 10 H₂O.
What are hydrates?Hydrates are the chemical compounds used to represent the water molecule (H₂O) in a compound. The water molecules are added to the compound formula as a crystalline structure.
The element tin is represented by the symbol Sn and chlorate is represented as (ClO₃)₂. The formula also has decahydrate which means it has ten molecules of water that can be represented by 10 H₂O.
The stock nomenclature is used to give the formula for the compound. The overall formula of the compound after adding the individual symbol will give, Sn(ClO₃)₂. 10 H₂O.
Therefore, Sn(ClO₃)₂ . 10 H₂O is a formula for tin (II) chlorate decahydrate.
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Q1: A stock solution containing Mn+2 ions was prepared by dissolving 1.584 g pure manganese metal in nitric acid and diluting to a final volume of 1.000 L. The following solutions were then prepared by dilution: For solution A, 50.00 mL of stock solution was diluted to 1000.0 mL. For solution B, 10.00 mL of solution A was diluted to 250.0 mL. For solution C, 10.00 mL of solution B was diluted to 500.0 mL. Calculate the concentrations of the stock solution and solutions A, B, and C.
The concentration of a solution is the amount of solute in a solution.
We have from the question that he mass of manganese = 1.584 g
Hence;
Amount of [tex]Mn^2+[/tex] = 1.584 g/55g/mol = 0.0288 moles
Recall that;
Number of moles = concentration * volume
Let the concentration of the solution be C
0.0288 moles = C * 1 L
C = 0.0288 moles/ 1 L
C= 0.0288 mol/L
Hence concentration of stock solution = 0.0288 mol/L
For solution A
From the dilution formula;
C1V1 = C2V2
where;
C1 = initial concentration
C2 = final concentration
V1 = initial volume
V2= final volume
C1 = 0.0288 mol/L
V1 = 50.00 mL
C2 = ?
V2 = 1000.0 mL
C2 = 0.0288 mol/L * 50.00 mL/1000.0 mL
C2 = 0.00144 mol/L
Hence, concentration of solution A is 0.00144 mol/L
For solution B
C1V1 = C2V2
C1 = 0.00144 mol/L
V1 = 10.00 mL
C2 = ?
V2 = 250.0 mL
C2 = 0.00144 mol/L * 10.00 mL/250.0 mL
C2 = 0.0000576 mol/L
Hence, concentration of solution B is 0.0000576 mol/L
For solution C
C1 = 0.0000576 mol/L
V1 = 10.00 mL
C2 = ?
V2 = 500.0 mL
C2 = 0.0000576 mol/L * 10.00 mL/500.0 mL
C2= 0.000001152 mol/L
Hence, concentration of solution C is 0.000001152 mol/L
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Suppose you are using distillation to separate cyclohexane and toluene. The boiling point of cyclohexane is Choose... oC and the boiling point of toluene is Choose... oC. Therefore, the liquid collected first should be Choose... .
Answer:
81°C
111°C
cyclohexane
Explanation:
Distillation is a process of separating two liquids based on differences in Bolling point. For two substances having different boiling points, they are collected as they are converted into vapour, condensed and move down the condenser one after the other.
Since the boiling point of cyclohexane is less than that of toluene, cyclohexane is collected first before toluene.
