Answer:
C
Explanation:
I believe the answer is C.
Chromatography
separates a solution based
on differences in how its
components ________in
different phases of matter.
It is often possible to change a hydrate into an anhydrous compound by heating it to drive off the water (dehydration). A 43.19 gram sample of a hydrate of MgBr2 was heated thoroughly in a porcelain crucible, until its weight remained constant. After heating, 27.21 grams of the anhydrous compound remained. What is the formula of the hydrate?
Answer:
[tex]\rm MgBr_2 \cdot 6\, H_2O[/tex].
Explanation:
Let [tex]x[/tex] denote the number of [tex]\rm H_{2}O[/tex] formula units for every [tex]\rm MgCl_{2}[/tex] formula unit. The formula of the hydrate would be [tex]{\rm MgBr_2} \cdot x\, {\rm H_2O}[/tex].
Look up the relative atomic mass of each element on a modern periodic table:
[tex]\rm Mg[/tex]: [tex]24.305[/tex].[tex]\rm Br[/tex]: [tex]79.904[/tex].[tex]\rm H[/tex]: [tex]1.008[/tex].[tex]\rm O[/tex]: [tex]15.999[/tex].Formula mass:
[tex]\begin{aligned}M({\rm MgBr_{2}}) &= 24.305 + 2 \times 79.904 \\ &= 184.113\; \rm g\cdot mol^{-1}\end{aligned}[/tex].
[tex]\begin{aligned}M({\rm H_{2}O}) &= 2 \times 1.008 + 15.999 \\ &= 18.015\; \rm g\cdot mol^{-1}\end{aligned}[/tex].
The anhydrous compound would be [tex]\rm MgBr_{2}[/tex]. There was [tex]27.21\; \rm g[/tex] of this compound. Calculate the number of moles of formula units in that much of this compound:
[tex]\begin{aligned}n({\rm MgBr_{2}}) &= \frac{m({\rm MgBr_{2}})}{M({\rm MgBr_{2}})} \\ &= \frac{27.21\; \rm g}{184.113\; \rm g \cdot mol^{-1}} \\ &\approx 0.1478\; \rm mol\end{aligned}[/tex].
During heating, [tex]43.19\; \rm g - 27.21\; \rm g = 15.98\; \rm g[/tex] of water [tex]\rm H_{2}O[/tex] escaped from the hydrate. Calculate the number of formula units in that [tex]15.98\; \rm g[/tex] of [tex]\rm H_{2}O\![/tex]:
[tex]\begin{aligned}n({\rm H_{2}O}) &= \frac{m({\rm H_{2}O})}{M({\rm H_{2}O})} \\ &=\frac{43.19\; \rm g - 27.21\; \rm g}{18.015\; \rm g \cdot mol^{-1}} \\&= \frac{15.98\; \rm g}{18.015\; \rm g \cdot mol^{-1}} \\ &\approx 0.887\; \rm mol\end{aligned}[/tex].
In other words, approximately [tex]0.1478\; \rm mol[/tex] of [tex]\rm MgBr_{2}[/tex] formula units (and hence the same number of moles of [tex]{\rm MgBr_2} \cdot x\, {\rm H_2O}[/tex] formula units) contain approximately [tex]0.887\; \rm mol[/tex] of [tex]\rm H_{2}O[/tex] formula units. Calculate the ratio between the two:
[tex]\begin{aligned}x &= \frac{n({\rm H_{2}O})}{n({\rm MgBr_2})} \\ &\approx \frac{0.1478\; \rm mol}{0.887\; \rm mol} \approx 6\end{aligned}[/tex].
Hence, the formula of the hydrate would be [tex]\rm MgBr_2 \cdot 6\, H_2O[/tex].
Which of the following processes is exothermic? Group of answer choices Allowing meat to thaw after taking it out of the freezer Popsicle melting on a warm summer day Boiling water in a beaker to convert it to steam Rolling a ball up a hill Reacting hydrogen and oxygen gases to make water
Answer:
Reacting hydrogen and oxygen gases to make water
Explanation:
Exothermic means that energy is released into the environment, so let's go through the process of elimination.
Allowing meat to thaw after taking it out of the freezer - NO it is endothermic, and takes energy/heat from the environment to thaw.
Popsicle melting on a warm summer day - NO also endothermic, the opposite of exothermic.
Boiling water in a beaker to convert it to steam - NO because we need to add heat, so it doesn't release any energy.
Rolling a ball up a hill - NO, for a ball to roll up a hill, it needs energy from something else, so it's not exothermic.
Reacting hydrogen and oxygen gases to make water - YES this reaction makes new bonds, which releases energy, so this is exothermic.
Among the following choices reacting hydrogen and oxygen gases to make water is an exothermic reaction as it releases energy as new bonds are formed.
What is an exothermic reaction?An exothermic reaction is defined as a chemical reaction which involves release of energy in the form of light,heat .In these reactions, energy is transferred from system to surroundings rather than taking energy from surroundings into system as in endothermic reactions.
In an exothermic reaction,change in enthalpy is negative.Therefore, it can be inferred that net amount of energy which is required to start the exothermic reaction is less than the net amount which is released by the reaction.
Examples of exothermic reactions are combustion reactions, detonation of nitroglycerin , neutralization reactions and nuclear fission.
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3. An atom
OF
elemente A has mass number 39 and 19 protons
Write the electron arrangement of the atom
Answer:
Explanation:
Potassium (K) atom has 19 electrons. The full electron configuration of Potassium (K) is 1s22s22p63s23p64s1
Principal energy level
Quantum number: n
1
2
3
4
5
6
Sublevels
availableQuantum number: l
1s
2s 2p
3s 3p 3d
4s 4p 4d 4f
5s 5p 5d 5f 5g
6s 6p 6d 6f 6g 6h
What happens when a chlorine atom gains an electron in its outer energy shell? A. It has an increase in the number of protons B. It becomes a negative ion C. It becomes a positive ion D. It has a decrease in the number of neutrons
Answer:
When a chlorine atom gains an electron, its outermost principal energy level achieves an octet. In this case, the ion has the same outermost shell as the original atom, but now that shell has eight electrons in it. Once again, the octet rule has been satisfied.
Explanation:
Question 3 of 10
How are prefixes used to name compounds?
O A. Prefixes are used to indicate the number of atoms in both
covalent and ionic compounds.
O B. Prefixes are used to tell how many of each kind of atom are in
covalent compounds.
O C. Prefixes are used to tell how many of each kind of atom are in
ionic compounds.
O D. A prefix is used only for the name of the second element in
covalent compounds.
the answer is highly possible to be C
Prefixes are used to indicate the number of atoms in both
covalent and ionic compounds.
Covalent or molecular compounds form when elements share electrons in a covalent bond to form molecules. Molecular compounds are electrically neutral.
Ionic compounds are (usually) formed when a metal reacts with a nonmetal (or a polyatomic ion). Covalent compounds are formed when two nonmetals react with each other. Since hydrogen is a nonmetal, binary compounds containing hydrogen are also usually covalent compounds.
Metal + Nonmetal —> ionic compound (usually)Metal + Polyatomic ion —> ionic compound (usually)Nonmetal + Nonmetal —> covalent compound (usually)Hydrogen + Nonmetal —> covalent compound (usually)Learn more about covalent and ionic compounds.
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what are stop signs from barack Obama?
Answer:
President Obama signs the Stop Trading on Congressional Knowledge Act in a ceremony at the White House. President Barack Obama delivers remarks prior to signing the STOCK Act in the South Court Auditorium at the Eisenhower Executive Building (EEOB) of the... sorry I have to hurryy
Explanation:
An element’s most stable ion forms an ionic compound with bromine, having the formula XBr2. If the ion of element "X" has a mass number of 230 and has 86 electrons, what is the identity of the element, and how many neutrons does it have?
Answer:
88
Explanation:
The ion has a charge of 2+, therefore the number of neutrons it possess is 86+2
which equals 88
The element X having a mass number of 230 and has 86 electrons is radium and has 142 neutrons.
An atom is composed basically of electrons, protons and neutrons. In a neutral atom, the number of protons and electrons are equal. The number of neutrons is the difference between the mass number and the number of protons (atomic number).
Since we know that the ion of the element X has 86 electrons and the compound formed is XBr2, it then means that neutral X has 88 electrons.
The number of electrons in the neutral atom is the same as the number of protons or atomic number. An element can be identified by its atomic number. The element having atomic number 88 is radium.
The number of neutrons is obtained as;
Mass number - atomic number
230 - 88 = 142 neutrons
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15. Sodium chloride is called an electrovalent compound whereas carbon dioxide is called covalent compound why?
Answer:
NaCl is an electrovalent compound because the sodium and chlorine atoms give one electron from their outermost shells to each other in order to complete their octets
Explanation:
Make me Brain liest plz );
3.7500 x 104 + 9.7100 x 105
Answer: [tex]1409.55[/tex]
Remove the 0's from each decimal number
[tex]3.7500 ---> 3.75\\9.7100 ---> 9.71[/tex]
Multiply
[tex]3.75*104=390\\9.71*105=1019.55[/tex]
Add
[tex]930+1019.55=1409.55[/tex]
Identify the type of energy described in each sentence. Tiles gravitational energy mechanical energy chemical energy electrical energy thermal energy nuclear energy radiant energy Pairs The body stores lipids ingested as fat and uses this energy when needed. arrowBoth (answer) A person's hat falls off and lands on the ground. arrowBoth (answer) A wave of water pushes a surfer to shore. arrowBoth (answer) A burner on a stove heats up a tea kettle. arrowBoth (answer) A power plant splits atoms to generate power for a city. arrowBoth (answer) A nerve sends an impulse to another nerve. arrowBoth (answer) A plant absorbs the Sun's rays to start the process of photosynthesis. arrowBoth (answer)
Answer:
The body stores lipids ingested as fat and uses this energy when needed-chemical energy
A person's hat falls off and lands on the ground- gravitational energy
A wave of water pushes a surfer to shore- mechanical energy
A burner on a stove heats up a tea kettle- thermal energy
A power plant splits atoms to generate power for a city- nuclear energy
A nerve sends an impulse to another nerve- electrical energy
A plant absorbs the Sun's rays to start the process of photosynthesis- radiant energy
Explanation:
Gravitational energy is energy stored by an object as a consequence of its height.
Mechanical energy is the energy that is possessed by an object due to its motion or due to its position.
Chemical energy refers to energy stored in chemical bonds in a substance.
Thermal energy is a form of energy that exists due to temperature difference between two bodies.
Nuclear energy refers to energy stored in the nucleus of an atom.
Electrical energy is a form of energy resulting from the flow of electric charge.
Radiant energy refers to energy that moves through vacuum without passing through a material medium.
How many molecules of sodium oxide will be created if 275 grams of sodium reacts with excess oxygen? Given the equation: 4Na + O2 -> 2Na2O
Answer:
3.60 x 10^24 molecules Na2O
Explanation:
phương trình nào sau đây không đúng
Mg(OH)2 (t°)→ MgO+H2O
Fe(OH)2 (t°,chân không)→FeO+H2O
2Fe(OH)3 (t°)→Fe2O3+3H2O
2NaOH (t°)→Na2O+H2O
Phương trình NaOH sai nha
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 RadioPhotometerWhich rule determines the charge on a monatomic ion formed from a nonmetal? group number ÷ 8 8 × group number 8−groupnumber groupnumber−8
Answer:
Group number – 8
Explanation:
To determine the charge on the ion formed by various elements, we simply consider their valence electrons.
However, this is only applicable to elements in group 1, 2 and 3 only.
To determine the charge on the ions formed by non metals i.e elements in group 4, 5, 6, 7 and 8(group 0) we simply subtract 8 from the group number i.e group number – 8
This can be further explained as follow:
Chlorine belong to group 7 because it has 7 valence electrons.
The charge on the chloride ion can be obtained as follow:
Group number = 7
Charge on ion =?
Charge on ion = Group number – 8
Charge on ion = 7 – 8
Charge on ion = – 1
Therefore, the charge on chloride ion is – 1.
What are easy ways to
Study Chemistry ??
Answer:
seneca
past papers
take notes from videos
Explanation:
very good website, asks questions about the subject correct for your exam board and gives correct answers and explanations
exam papers always help
1. Which material had the highest rate of absorption? What can you conclude about the rate
of absorption in the natural world? How might this influence climate regions?
it might be porous materials
Answer:
Air had the highest rate of absorption. Air absorbs most of the suns heat and sun rays and air can move to different areas which are warm and colder.
Explanation:
What is a base?
A. A substance that increases the concentration of oxygen in
solution
B. A substance that increases the concentration of OH ions in
solution
C. A substance that increases the concentration of H+ ions when dissolved
D. A substance that contributes chloride ions to the solution
Answer:
A base releases OH~ in a solution, so the answer is B
If you have a little air in a balloon, find the volume of the balloon if the mass is 0.6 g and the density of the air is 0.0012 g / mL
Hey there!:
Mass = 0.6 g
Density = 0.0012 g/mL
Volume = ??
Therefore :
Density = mass / Volume
0.0012 = 0.6 / V
V = 0.6 / 0.012
V = 500 mL
Hope this helps!
Which of the following increases as you move up a column of the periodic table?
Number of electrons
Atomic radius
Atomic Number
Electronegativity
Answer:
electronegativity increases
Citrus fruits may taste sour because they are _____. acidic basic neutral too ripe
Answer:
A. acidic
Explanation:
Citrus fruits may taste sour because they are acidic. They have citric acid and ascorbic acids.
How are reactivity and electronegativity related? 1 point)
. An element will be more reactive if it has a very high or very low electronegativity
Elements with lower electronegativity are more reactive than elements with higher electronegativity
Elements with higher electronegativity are more reactive than elements with lower electronegativity
Anmentess reactive it has a very high or very low electronegativity
Elements which have high electron negativity are more reactive than elements with low electron negativity.
This is because elements with high electron negativity will gain more electrons to become more stable.
When electron negativity of an element decrease it becomes more into its element form.
There will be more ionization energy of the elements who have more electron negativity.
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Answer: An element will be more reactive if it has a very high or very low electronegativity.
Is your answer
What is occurring during boiling?
A. Solvent particles increase in kinetic energy until they knock solute particles out of the solution and into the air.
B. Solute particles increase in kinetic energy until they knock solvent particles out of the solution and into the air.
C. Vapor pressure is greater than atmospheric pressure and water molecules escape from the solution into the air.
D. Atmospheric pressure is greater than vapor pressure, and water molecules escape from the solution into the air.
Reset Selection
Answer:
D: Atmospheric pressure is greater than vapor pressure,and water molecules escape from the solution into the air.
Atmospheric pressure is greater than vapor pressure, and water molecules escape from the solution into the air, which occurs during boiling. The correct option is D.
What is boiling?Boiling is a process when more heat is given to any liquid, it starts to boil. When the temperature is increased, boiling happens, but only in liquid. The molecules of liquid start to turn into vapor and start to escape into the atmosphere.
It is also called the vaporization of the liquid. The boiling points of different liquids are different, and they start to boil at their own temperature.
Thus, the correct option is D. Water molecules escape from the solution into the air when atmospheric pressure exceeds vapor pressure.
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Hydrogen and oxygen combine in
the ratio of 1:8 by mass to form
water. What mass of oxygen gas
would be required to react
completely with 3 g of hydrogen
gas?
Answer:
hhshshhxujejushwhbwhsjs s hs
Technician A says that the freezing point of a substance is the temperature at which the substance changes state from a solid to a liquid. Technician B says that the freezing point of a substance is the temperature at which the substance changes state from a liquid to a solid. Who is correct
Answer: Technician B
Explanation:
Technician B is correct. The freezing point of a substance is the temperature at which the substance changes state from a liquid to a solid.
Technician A is incorrect. On the other hand, the melting point of a substance is the temperature at which the substance changes state from a solid to a liquid.
ocean in ionnic bonding, during the transfer of electrons between two neutrally charged atoms, one electron moves from one atom to another. What are the new relative charges between two atoms
Answer: The new relative charges between two atoms are +1 and -1 for cation and anion respectively.
Explanation:
When an atom accepts an electron, negative charge is created on atom and is called as anion.
When atom loses an electron, positive charge is created on atom and is called as cation.
For formation of a neutral ionic compound, the charges on cation and anion must be balanced. The cation is formed by loss of electrons by metals and anions are formed by gain of electrons by non metals.
Thus when one electron is lost by an atom it forms one positive charge and when one electron is gained by an atom it forms one negative charge.
Foe example: sodium atom loses its one valance electron and form cation [tex]Na^+[/tex]. Chlorine atom gain one electron and form anion [tex]Cl^-[/tex]. they both combine to form sodium chloride through ionic bond.
please help ASAP please!!
Answer:
If I am correct the last one because the pressure is decreasing and the temperature is increasing
Which are the physical properties of water
is a corroding metal a physical or chemical change?
Answer:
Corrosian is a chemical change
Explanation:
giúp tớ với, mình học lớp 9 ạ
Answer: broooo what is this
Explanation: