why is an element considered a pure substance
Answer:
Because they cannot be separated into more then one type of substance.
Explanation:
Answer:
Elements are made of only one kind of atom. The particles can be a single atom or a molecule made of only one kind of atom. There is no physical change that can separate elements into more than one kind of substance. This makes an element a pure substance.An element is made up of only one type of atom. An element cannot be broken down into a simpler form.
if 193 ml of chlorine gas was collected at 21 celsius, what volume would it have if the temperature dropped to 0 celsius
Answer:
New volume of chlorine gas (V2) = 179 ml (Approx)
Explanation:
Given:
Volume of chlorine gas (V1) = 193 ml
Temperature of chlorine gas (T1) = 21°C = 21 + 273 = 294 k
New temperature of chlorine gas (T2) = 0°C = 0 + 273 = 273 k
Find:
New volume of chlorine gas (V2) = ?
Computation:
Using charle's law
V1 / T1 = V2 / T2
193 / 294 = V2 / 273
V2 = 179.21
New volume of chlorine gas (V2) = 179 ml (Approx)
How many moles are present in 136 grams of MgCl2? 1.46 mol 1.43 mol 2.27 mol
Answer:
1.43 mol
Explanation:
45. The following data was collected for 3 compounds:
Mass of Nitrogen that combines with 1 g of Oxygen
Compound A 1.750 g
Compound B 0.8750 g
Compound C 0.4375 g
Show whether these are the same or different compounds. What chemical law is being observed here?
Answer:
The three compounds are different compounds
Explanation:
The mass of Nitrogen that combines with 1 gram of Oxygen in Compound A = 1.750 g
The mass of Nitrogen that combines with 1 gram of Oxygen in Compound B = 0.8750 g
The mass of Nitrogen that combines with 1 gram of Oxygen in Compound C = 0.4375 g
According to the law of multiple proportions, when atoms of two different elements react to form compounds, the masses of one of the elements that combines with a fixed mass of the other element are in small whole number ratios.
The ratio of the masses are;
Mass of Nitrogen in Compound B/(Mass of Nitrogen in Compound C = 0.8750/0.4375 = 2
Mass of Nitrogen in Compound A/(Mass of Nitrogen in Compound C = 1.750/0.4375= 4
Mass of Nitrogen in Compound A/(Mass of Nitrogen in Compound B = 1.750/0.8750= 2
Given that the masses of Nitrogen in the three compounds are in small whole number ratios, the three compounds, Compound A, Compound B, and Compound C are different compounds.
Charles is given two electrical conductors – aluminium and graphite. Help him to select one for making an electric wire. Justify your reason.
Answer:
I think the answer is aluminium because both graphite and Al are good conductors of electricity but Al is more ductile than graphite. also pls mark as Brainilest.
Explanation:
Which of the following elements has a complete outer shell of electrons? A. Iron (Fe) B. Hydrogen (H) C. Neon (Ne) D. Nitrogen (N)
Answer:
The answer is Neon
Answer:
neon
Explanation:
neon has a complete outer 2n shell
Ou Esaplain different form
of oxygen?
Answer:
oxygen is the chemical element with the atomic number is 8 and the symbol is o its known as called oxygen.
Explanation:
Oxygen is the most third element in the universe at they standard and temperature and pressure,and oxides most elements as other compounds.
Oxygen gas is the earth atmosphere is 21%, an oxygen is the half of the earth crust in form of oxide,oxygen is liquid and solid gas.
Oxygen atoms such as proteins and acids, fats the major organic compounds, oxygen as component of the water and carbon dioxide.
Oxygen has many characteristics :- properties and molecular structure:-
this is a pressure and temperature with molecular formula referred as oxygen,simply describe a double bond and molecular orbits.
Physical properties:- oxygen is highly substance and must be combustible materials, oxygen may also from using a liquid nitrogen coolant, molecular oxygen is the associated with the process of air glow.
Stellar origin :- all of the remaining to half lives to the majority of are less then milliseconds.
Occurrence:- oxygen is the process part of the element in the earth crust, free oxygen is also occurs in the world bodies.
Analysis :- analysis to the structure of vegetation and the carbon cycle on a global scale.
When a substance's particles are packed together tightly and have a definite shape and
volume...it is said to be in what state?
solid
gas
plasma
liquid
Answer:
solid
Explanation:
What scientific instrument is sensitive enough to detect a planet transiting a star?
Answer:
Photometer
Explanation:
A photometer (photo comes from the Greek for light) measures the light coming from 140,000 stars in Kepler's stationary field of view. If a planet transits (passes in front of) any star the amount of light from the star is reduced enough so that the photometer senses it and relays the information back to the Kepler team.
Scientific instruments are tools used for researching the universe and natural sciences. A Photometer is sensitive enough to detect a planet transiting a star. Thus, option D is correct.
What is a Photometer?A Photometer is a device that converts light energy into electrical voltage by the photoelectric effect given by Einstein. It uses Quantum mechanics to convert the energy possessed by the photons and electrons. It follows Ohm's law to convert energy.
It is used to detect the planets transiting stars as they can detect the light energy as it uses the electromagnetic radiation of various wavelengths to convert them by the photodiode, resistor, and a multiplier.
Therefore, option D. a photometer is used to detect the planets in the universe transiting stars.
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Your question is incomplete, but most probably your full question was, What scientific instrument is sensitive enough to detect a planet transiting a star?
Atomic force microscopeSolar arraysSatellite RadioPhotometerHow many moles of potassium in 73.56g of potassium chlorate (V) (KClO 3 )?
Answer:
Approximately [tex]0.6003\; \rm mol[/tex] formula units.
Explanation:
Formula Mass of KClO₃Look up the relative atomic mass data for [tex]\rm K[/tex], [tex]\rm Cl[/tex], and [tex]\rm O[/tex] on a modern periodic table:
[tex]\rm K[/tex]: [tex]39.908[/tex].[tex]\rm Cl[/tex]: [tex]35.45[/tex].[tex]\rm O[/tex]: [tex]15.999[/tex].The relative atomic mass of an element is numerically equal to the mass (in grams) of one mole of its atoms. For example, the relative atomic mass of [tex]\rm K[/tex] is [tex]39.908[/tex]. Therefore, the mass of one mole of [tex]\rm K\![/tex] atoms should be [tex]39.908\; \rm g[/tex].
Each [tex]\rm KClO_3[/tex] "formula" unit includes one [tex]\rm K[/tex] atom, one [tex]\rm Cl[/tex] atom, and three [tex]\rm O[/tex] atoms. Therefore, one mole of [tex]\rm KClO_3\![/tex] formula units would include:
one mole of [tex]\rm K[/tex] atoms, one mole of [tex]\rm Cl[/tex] atoms, and three moles of [tex]\rm O[/tex] atoms.From the relative atomic mass of these three elements:
The mass of one mole of [tex]\rm K[/tex] atoms would be [tex]39.908\; \rm g[/tex].The mass of one mole of [tex]\rm Cl[/tex] atoms would be [tex]35.45\; \rm g[/tex].The mass of three moles of [tex]\rm O[/tex] atoms would be [tex]3 \times 15.999\; \rm g = 47.997\; \rm g[/tex].Combining these three parts should give the mass of one mole of [tex]\rm KClO_3[/tex] formula units:
[tex]\begin{aligned}& M(\mathrm{KClO_3}) \\ &= 39.908 + 35.45 + 3 \times 15.999 \\ &= 122.545\; \rm g \cdot mol^{-1}\end{aligned}[/tex].
Number of moles of KClO₃ formula units in the sampleThe formula mass of [tex]\rm KClO_3[/tex] is [tex]M(\mathrm{KClO_3}) = 122.545\; \rm g \cdot mol^{-1}[/tex], meaning that the mass of one mole of [tex]\rm KClO_3\![/tex] formula units would be [tex]122.545\; \rm g\![/tex].
The mass of this [tex]\rm KClO_3\!\![/tex] sample is [tex]m(\mathrm{KClO_3}) = 73.56\; \rm g[/tex]. The number of moles of formula [tex]\rm KClO_3\![/tex] units in this sample would be:
[tex]\begin{aligned}n(\mathrm{KClO_3}) &= \frac{m(\mathrm{KClO_3})}{M(\mathrm{KClO_3})} \\ &= \frac{73.56\; \rm g}{122.545\; \rm g \cdot mol^{-1}} \approx 0.6003\; \rm mol\end{aligned}[/tex].
To know the exact number of mole of potassium (K) in 73.56 g of potassium chlorate (v), KClO₃ do the following:
Step 1:Determination of the number of mole in 73.56 g of potassium chlorate (v), KClO₃
Mass of KClO₃ = 73.56 g
Molar mass of KClO₃ = 39 + 35.5 + (16×3)
= 39 + 35.5 + 48
= 122.5 g/mol
Mole of KClO₃ =?[tex]Mole =\frac{mass}{molar mass}\\\\Mol KClO_{3} = \frac{73.56}{122.5}[/tex]
Mole of KClO₃ = 0.6 moleStep 2:Determination of the number of mole of potassium, K in 0.6 mole (i.e 73.56 g) of KClO₃
Considering the molecular formula of potassium chlorate (v), KClO₃, we can see that:
1 mole of KClO₃ contains 1 mole of K.
Therefore, 0.6 mole of KClO₃ will also contain 0.6 mole of K.
Therefore, we can conclude that 73.56 g of KClO₃ contains 0.6 mole of potassium, K.
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3.0 cm x 4.0 cm x 1.0 cm
[?]cm^3
Explanation:
Hi there!!
you asked to multiply these all right,
you can simply multiply it ,
=3cm × 4 cm × 1cm
= 12cm^2×1cm (4×3=12)
= 12cm^3 (12×1=12)
Therefore, theanswer is 12 cm^3.
Hope it helps..
Chemical change example
Answer: burning paper
Explanation:
The paper burns in air to form smoke and ash. which makes it a chemical change.
You are given two aqueous solutions with different ionic solutes (Solution A and Solution B). What if you are told that Solution A has a greater concentration than Solution B by mass percent, but Solution B has a greater concentration than Solution A in terms of molality? Is this possible? If not, explain why not. If it is possible, provide example solutes for A and B and justify your answer with calculations.
Answer:
Yes, it is possible. Let us consider an example of two solutions, that is, solution A having 20 percent mass RbCl (rubidium chloride) and solution B is having 15 percent by mass NaCl or sodium chloride.
It is found that solution A is having more concentration in comparison to solution B in terms of mass percent. The formula for mass percent is,
% by mass = mass of solute/mass of solution * 100
Now the formula for molality is,
Molality = weight of solute/molecular weight of solute * 1000/ weight of solvent in grams
Now molality of solution A is,
m = 20/121 * 1000/80 (molecular weight of RbCl is 121 grams per mole)
m = 2.07
Now the molality of solution B is,
m = 15/58.5 * 1000/85
m = 3.02
Therefore, in terms of molality, the solution B is having greater concentration (3.02) in comparison to solution A (2.07).
describe melting of a solid
which state of matter is Na OH(s)
Explanation:
SOLID
Sodium hydroxide exists in the solid phase at room temperature. You would find it in the lab as hemispherical white solid pellets. The phase of a substance depends on temperature and pressure. As you heat a solid, it will melt and change to the liquid phase.
methyl phenolphthalein and litmus
Answer:
Both are the indicators which helps to identity the acid and base
Answer:
Types of indicators which show if the solution is an acid , alkali or a natural
Explanation:
You add one of two drops of the indicator into a solution and then it would be in a scale from red to purple and this is called a PH scale which shows if it's an acid, alkali or a natural solution red being a strong acid with the PH number of one , green being a natural solution with the PH number of 7 and an alkali being purple with the PH number of 14
Hope this helps :)
What three things are required for a fire to start?
A hot metal plate at 150°C has been placed in air at room temperature. Which event would most likely take place
over the next few minutes?
Molecules in both the metal and the surrounding air will start moving at lower speeds.
Molecules in both the metal and the surrounding air will start moving at higher speeds.
The air molecules that are surrounding the metal will slow down, and the molecules in the metal will speed up
The air molecules that are surrounding the metal will speed up, and the molecules in the metal will slow down
Answer:
d
Explanation:
Scientists from different fields are trying to understand how the global climate is reacting to the changes caused in nature, and by human activities. They have come up with conflicting interpretations. Which of these is the most likely outcome of differences in interpretations made by scientists on the issue of global climate?
Answer:
New ideas would be created and tested
Explanation:
All old ideas would be discarded.
Scientific evidence would be weakened.
New ideas would be created and tested.
The limitations of science would be evident.
In science, old ideas are usually improved or modified and not entirely discarded. The old ideas form the basis for new ideas after extensive reviews. Differences in the interpretations made by scientists on any particular phenomenon give rooms for reviews. The reviews often generate new ideas or hypotheses and these can be tested using relevant experimental procedures according to the scientific method.
Hence, the correct answer would be that new ideas would be created and tested.
Which of the following is a characteristic property of noble gases? A. They only react with each other B. They do not react chemically C. They react violently in water D. They react violently in air.
Answer:
B.They do not react chemically
Explanation:
This is because all noble gases haves full outer shell therefore they don’t participate in bonding.They are referred to as inert which means unreactive.
Answer:
They do not react chemically
Explanation:
Calcula el %m/v de alcohol en una mezcla utilizada para la desinfección de manos formada por: 15 ml de agua (densidad=1g/ml), 105 g de etanol (densidad: 0,798 g/ml) y 4,5 gramos de jabón líquido (densidad= 1,5 g/ml)
Answer:
%m/v =70%
Explanation:
El %m/v es una unidad de concentración que se define como cien veces la división entre la masa de una sustancia (En gramos) y el volumen total en el que esta sustancia se encuentra (en mL).
En el problema, debemos hallar la masa de etanol (Alcohol) y el volumen total de la solución.
Masa alcohol:
Ya te la dan en el problema: 105g
Volumen solución:
Volumen agua: 15mL
Volumen etanol: 105g × (1mL / 0.798g) = 131mL
Volumen Jabón líquido: 4.5g × (1mL / 1.5g) = 3mL
Volumen: 15mL + 131mL + 3mL
149mL
Así, el %m/v de alcohol en la solución es:
%m/v = (105g / 149mL) × 100
%m/v =70%
In human cells, a dynamic equilibrium exists between carbonic acid (H2CO3) and carbon dioxide (CO).
H2CO3(aq) = CO2() + H200
When a person exercises, the body's cells metabolize glucose to gain energy. This metabolism also causes an increase in the
concentration of carbon dioxide.
Le Chatelier's principle states that stresses applied to a system in dynamic equilibrium will cause the system to change in order to
alleviate those stresses. According to this principle, how would an increase in carbon dioxide concentration affect the system?
A. There would be a decrease in the concentration of carbonic acid.
В. There would be an increase in the concentration of glucose.
C. There would be an increase in the concentration of water.
There would be an increase in the concentration of carbonic acid.
D There would be an increase in the concentration of carbonic acid.
There would be an increase in the concentration of carbonic acid - this is how an increase in carbon dioxide concentration influences the system.
What is dynamic equilibrium?In chemistry, a dynamic equilibrium lives once a reversible reaction occurs. Substances transition between the reactants and products at equal rates, indicating there is no net change. Reactants and products exist formed at such a rate that the concentration of neither changes. It is a precise example of a system in a steady state. After a time, a reversible reaction in a closed system can get what we call a dynamic equilibrium.
The correct answer is option D.
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Ethane- (-89) Butane- (0) Methanol- (64.7) Hexane- (69) Pentadecane- (270) Heptadecane- (302) a) A mixture of pendtadecane and heptadecane can be separated by______ b) Which pair of compounds are easiest to separate (i) Ethane and Pentadecane (ii) Ethane and Heptadecane (iii) Butane and Hexane (iv) Butane and Heptadecane
Answer:
(ii) Ethane and Heptadecane
Explanation:
The separation of all the species listed in the answer options for the question depends on the molar mass of each specie.
Ethane is a low molecular mass gas. It exists in the gaseous state at room temperature. However, heptadecane appears as a liquid because it has a greater relative molecular mass.
It is very easily to distinguish between the gas, ethane and the liquid heptadecane which is a high molecular mass alkane, hence the answer.
es with hydrogen
atoms
Fill the valencies with
C
+
() C c-c=c
(ii)
(
c
C - C = C
/
c
(ii)
c
- C
با
-
1
c - c
С — С
co
Answer:
all u have to do is inserting hydrogen atoms where it's possible, if carbon is not bonded to any element, then it can have 4 hydrogens. for the first chain, the first carbon can have 3 hydrogen atoms, the second carbon 1 hydrogen atom only the third also 1 hydrogen since there is double bond and the 4th 2 hydrogen atoms
Answer:
a rat and a cat can have sex
xD
Explanation:
In common speech, some people may use the terms hypothesis and theory interchangeably. In science, however, the terms have different meanings. What do you think is an important difference between a hypothesis and a theory?
Answer: In science, a hypothesis is a possible explanation for an observation, while a theory is an explanation that is supported by a large body of evidence.
Explanation: exact answer
What is Entropy?
A. The opposite of Enthalpy
B. The temperature at which a reaction is feasible.
C. Free energy used for a reaction.
D. A measure of disorder,
Answer:
D.) A measure of disorder
Explanation:
I got it correct on founders edtell
Do you think it’s important that forensics is categorized as a science? Why or why not?
Match the chemical equation with the correct reaction type:
Column A
Column B
1.
Fe +52 - Fe253
2.
Pb(NO3)2 + K2CrO 4 PbCrO 4 +KNO3
a. single replacement
b. double replacement
C. decomposition
3.
H2 + N2 + NH3
d. combustion
4.
Fe + CuCl2 - FeCl2 + Cu
e synthesis
5.
KCIO3 -KCI + O2
6.
Mg + HCI-H2 + MgCl2
7.
C3Hg + O2 CO2 + H2O
8.
Zn + HCI - ZnCl2 + H2
9.
NH3-N2 + O2
10.
AgNO3 + Cu Cu(NO3)2 + Ag
f70X
1.
Fe +52 - Fe253
SYNTHESIS REACTION
A synthesis reaction occurs when two or more reactants combine to form a single product.
2.
Pb(NO3)2 + K2CrO 4 PbCrO 4 +KNO3
DOUBLE REPLACEMENT
A double-replacement reaction exchanges the cations (or the anions) of two ionic compounds.
3.
H2 + N2 + NH3
SYNTHESIS REACTION
A synthesis reaction occurs when two or more reactants combine to form a single product.
4.
Fe + CuCl2 - FeCl2 + Cu
SINGLE REPLACEMENT
A single-displacement reaction, is a chemical reaction in which one element replaces an/other element in a compound.
Note. An element can only replace an element that it is higher than in the electrochemical series or an element that is less reactive than itself.
5.
KCIO3 -KCI + O2
DECOMPOSITION REACTION
A decomposition reaction is a reaction in which a compound breaks down into two or more simpler substances.
Most times this type of reaction requires an in put of energy.
It is usually an endothermic reaction as heat is mostly absorbed.
6.
Mg + HCI-H2 + MgCl2
SINGLE REPLACEMENT
A single-displacement reaction, is a chemical reaction in which one element replaces an/other element in a compound.
Note. An element can only replace an element that it is higher than in the electrochemical series or an element that is less reactive than itself.
7.
C3Hg + O2 CO2 + H2O
COMBUSTION REACTION
Combustion reaction is a high-temperature exothermic redox chemical reaction between a fuel (example propane C3H8) and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products.( mostly C02)
It can also be referred to as burning.
Combustion reaction is one of the chemical characteristics of hydrocarbons.
8.
Zn + HCI - ZnCl2 + H2
SINGLE REPLACEMENT
A single-displacement reaction, is a chemical reaction in which one element replaces an/other element in a compound.
Note. An element can only replace an element that it is higher than in the electrochemical series or an element that is less reactive than itself.
9.
NH3-N2 + O2
DECOMPOSITION REACTION
A decomposition reaction is a reaction in which a compound breaks down into two or more simpler substances.
Most times this type of reaction requires an in put of energy.
It is usually an endothermic reaction as heat is mostly absorbed.
10.
AgNO3 + Cu Cu(NO3)2 + Ag
f70X
SINGLE REPLACEMENT
A single-displacement reaction, is a chemical reaction in which one element replaces an/other element in a compound.
Note. An element can only replace an element that it is higher than in the electrochemical series or an element that is less reactive than itself.
Explain the different between a molecule and a compound.
Answer:
-A molecule is the smallesr part is compound whereas a compound is the combination of two or more atoms in a fixed proportion by wiehgt.
- A glass of water is an example of compound but a small portion of water can be called molecule.
Answer in the correct significant figures: 31.2 x 4.13*
Answer:
1.29* 10^2
Explanation:
multiply them and then round
