Answer:
0.208 mol B
Explanation:
There are 6.02 × 10^23 atoms in one mole of a substance, according to Avagadro's law.
According to this question, there are 1.25 x 10^23 atoms of Boron. This means that the number of moles in the Boron atom can be calculated thus:
number of moles (n) = number of boron atoms (nA) ÷ Avagadro's number
n = 1.25 x 10^23 ÷ 6.02 × 10^23
n = 0.2076 × 10^(23-23)
n = 0.208 × 10^0
n = 0.208 × 1
n = 0.208 moles of Boron
How many grams of NH3 can be dissolved in 50 grams of water at 50oC?
15 grams of NH3 can be dissolved
Further explanationGiven
50 grams of water at 50°C
Required
mass of NH3
Solution
Solubility is the maximum amount of a substance that can dissolve in some solvents. Factors that affect solubility
1. Temperature: 2. Surface area: 3. Solvent type: 4. Stirring process:We can use solubility chart (attached) to determine the solubility of NH3 at 50°C
From the graph, we can see that the solubility of NH3 in 100 g of water at 50 C is 30 g
So that the solubility in 50 grams of water is:
= 50/100 x 30
= 15 grams
Leon is creating a model using the items in the picture below. How could he best improve his model?
O
Earth
Moon
Sun
Make the earth larger than the sun
Make the moon larger than the sun
Make the sun smaller than the earth
Make the moon smaller than the earth
Make the moon smaller than the Earth.
What is the mass of 0.55 mole
of magnesium chloride?
Answer:
SYMBOLS, FORMULAS AND MOLAR MASSES
OBJECTIVES
1. To correctly write and interpret chemical formulas
2. To calculate molecular weights from chemical formulas
3. To calculate moles from grams using chemical formulas
INTRODUCTION
Part I. Symbols and formulas
An element is a homogeneous pure substance made up of identical atoms. All matter is made
up of elements and, since chemistry is the study of matter, it is convenient to use symbols to represent
the elements rather than using the entire name.
By international agreement, specific symbols are assigned to each element (Note: This means
that while names of the elements vary with language, symbols are constant throughout the world.) Each
element is assigned a one- or two-letter symbol. The first letter is capitalized, the second (if there is
one) is not. While this often seems trivial, it is in fact a very important point. For example, in chemical
language Co represents cobalt, which is a metal and an element, while CO represents carbon monoxide,
a compound which is a colorless, odorless gas! Even when there is not an obvious correspondence,
for instance "MN", it can cause confusion. Do you mean the element manganese? Did you forget a
letter and mean something else? Are you using "M" to represent something else entirely? Chemists
sometimes use "M" to represent any metal. It is well worth the trouble to memorize the symbols for
common elements.
Since compounds consist of elements, the chemical formulas of compounds also consist of
elements with subscripts used to denote the number of atoms per molecule. If there is no subscript, it is
implied that there is one of that kind of atom. Ones never appear in chemical formulas. Not only do
subscripts denote ratios of atoms, they also denote the ratio of moles of element to one mole of
compound. Parentheses can be used to show groups of atoms, with the subscripts showing how many
groups there are. Parentheses are not used if there is only one group.
Examples: For one mole of the following compounds, how many moles of each element are
present?
MgCl2 1 mole Mg, 2 moles Cl
Mg(NO3)2 1 mole Mg, 2 moles N, 6 moles O
NaNO3 1 mole Na, 1 mole N, 3 mole O
AgCl 1 mole Ag, 1 mole ClPart II. Molar Masses
Each atom has a different size and therefore a different mass. The relative masses of each
element can be found on the periodic table. For example, one atom of magnesium weighs 24.31 amu
(atomic mass units). However, one mole of magnesium weighs 24.31 g. (Moles were planned that
way!) Since one mole of MgCl2 consists of one mole of magnesium and two moles of chlorine, the
mass of one mole of MgCl2 must be the sum of the masses of the elements. The mass of one mole of a
substance is called the molar mass or molecular weight.
Examples: What is the molar mass of the following compounds?
MgCl2 24.31 + 2(35.45) = 95.21 g/mol
Mg(NO3)2 24.31 + 2(14.01) + 6(16.00) = 148.33 g/mol
NaNO3 23.00 + 14.01 + 3(16.00) = 85.01 g/mol
AgCl 107.9 + 35.45 = 143.4 g/mol
(Note: Yes! You DO have to count significant figures when calculating molecular weight/molar
mass. However, the number of significant figures may vary depending on which periodic table you use.)
Chemists are generally interested in number of moles. Unfortunately, it is impossible to measure
moles directly. However, masses are easily measured, and if the chemical formula of the compound is
known, the molar mass can be used to determine the number of moles. The molar mass is defined as:
molar mass = grams/moles = g/mol (1)
Moles may be calculated by using molar mass as a conversion factor in dimensional analysis where
molar mass in grams = 1 (exactly) mole of compound (2)
This method is used in multi-step calculations. For example, if 0.873 g of MgCl2 is weighed out, it
is 9.17 x 10-3
moles.
1 mole
0.873g x 95.21 g = 9.17 x 10-3
mol MgCl2 (3)
However, 0.873 g of AgCl is only 6.09 x 10-3
mol.
1 mole
0.873g x 143.4 g = 6.09 x 10-3
mol AgCl (4)Molar mass may also be used to relate moles to grams. For example, 0.158 mol of MgCl2 is 15.2 g.
0.158 mol x 95.21 g = 15.2 g MgCl2 (5)
1 mol
Percent is used to express parts per one hundred. Usually in chemistry, it refers to
g of species of interest x 100 = % (6)
g of whole thing
Example: For the % Mg in MgCl2: In one mole of MgCl2, there are 24.31 g of Mg (molar mass of Mg,
the part we are interested in) and 95.21 g of MgCl2 (the whole thing), so %Mg in MgCl2 is
(24.31/95.21) x 100 = 25.53% Mg (7)
PROCEDURE
Work individually.
The formula for calcium phosphate is Ca3(PO4)2. Weigh about 2 g of calcium phosphate to the
nearest 0.001 g. In other words, you do not have to have exactly 2.000g, but you must know the
weight you have exactly. Acceptable results include but are not limited to: 1.985g , 2.035g, 2.314g
etc.
Be sure to report all results with the correct number of significant figures and appropriate units!
Which statement below best describes the difference between an orbit and an orbital?
a. An orbit is a fixed path around the nucleus where an electron must be found; an orbital is a probability region where an electron is likely (but
not necessarily) going to be found
b. An orbit and an orbital are the same thing
c. An orbital is a fixed path around the nucleus where an electron must be found; an orbit is a probability region where an electron is likely (but
not necessarily) going to be found
Answer:
An orbit is a fixed path around the nucleus where an electron must be found; an orbital is a probability region where an electron is likely (but
not necessarily) going to be found
Explanation:
Orbits are fixed elliptical paths where an electron must be found. The idea of orbits was introduced in the Bohr model of the atom. Electrons were shown to occupy fixed orbitals of quantized energy.
Orbital is an idea introduced by quantum mechanics. It refers to a region in space where an electron may be found. The wave mechanical approach does not view the electron as being found in a fixed orbital but rather defines a region in space around the nucleus where there is a high probability of finding the electron.
Help please!! I'll name you brainliest!!
Answer:
magesium di chloride
Explanation:
it has one magnesium and 2 chlorines
Answer:
Magnesium Chloride
WHICH VIRAL REPRODUCTION CYCLE HAD THE VIRUS PUTTING ITS GENETIC MATERIAL INTO THE CELL
A. lytic cycle
B. lysogenic cycle
C. both
Does gases have a kinetic attraction? Yes or no.
Answer:
No
Explanation:
There are no interactive forces (i.e., attraction or repulsion) between the particles of a gas.
The average kinetic energy of gas particles is proportional to the absolute temperature of the gas, and all gases at the same temperature have the same average kinetic energy.
How many molecules are contained in 125 grams of water, H20?
Answer:18.015 g
Explanation:
Water has a molar mass of 18.015 g/mol . This means that one mole of water molecules has a mass of 18.015 g . So, to sum this up, 6.022⋅1023 molecules of water will amount to 1 mole of water, which in turn will have a mass of 18.015 g
Question 9(Multiple Choice Worth 1 points)
(05.03 LC)
Which of the following stars usually shine with the dimmest of light?
O Dwarfs
O Giants
O Main sequence stars
O Supergiants
If a balloon containing 3000 L of gas at 39°C and 99 kPa rises to an altitude where the pressure is 45.5 kPa and the temperature is 16°C,
the volume of the balloon under these new conditions would be calculated using the following conversion factor ratios:
( the one I have marked, I’m not sure if that’s the answer or not )
[tex]\tt =3000~L\times \dfrac{289}{312}\times \dfrac{99}{45.5}[/tex]
Further explanationGiven
3000 L of gas at 39°C and 99 kPa to 45.5 kPa and 16°C,
Required
the new volume
Solution
Combined with Boyle's law and Gay Lussac's law
[tex]\tt \dfrac{P_1.V_1}{T_1}=\dfrac{P_2.V_2}{T_2}[/tex]
T₁ = 39 + 273 = 312
T₂ = 16 + 273 = 289
Input the value :
V₂ = (P₁V₁.T₂)/(P₂.T₁)
V₂ = (99 x 3000 x 289)/(45.5 x 312)
or we can write it as:
V₂ = 3000 L x (289/312) x (99/45.5)
Ethylene glycol (C2H6O2) is used as an antifreeze in cars. If 250 g of ethylene glycol is added to 3.00 kg of water, what is the molality? Calculate how much the freezing point of water will be lowered. The freezing-point depression constant for water is Kf = –1.86°C/m. Show your work.
Answer:
2,909 M
Explanation:
molair mass is of.ethylene is 26,04 g/mol
first you need to calculate how much mL 3 kg is. You can do this by using the density of ethylene: 1,1 g/mL.
3000 g x 1.1 = 3300 mL = 3,3 L
Next you need to calculate the amount of moles:
250 g / 26,04 g/mol = 9,60 mol
Now you can calculate the molarity:
9,6/3.3 = 2,909 M
I don't know the answer for the second question. I'm sorry.
How many atoms are in 4.72 moles or Ar?
Answer:
Argon is a chemical element with the symbol Ar and atomic number 18.
Explanation:
Answer:
Avogadro's number is a very important relationshiptoremember: 1 mole = 6.022×1023 6.022 × 1023atoms, molecules, protons, etc.
...
Explanation:
jayfeather friend me
Isotopes of the same element must have the same
A. atomic number
B. mass number
C. number of nucleons
D. number of neutrons
Answer:
D. number of neutrons
Explanation:
Isotopes of the same element must have the same number of neutrons. Neutrons of an atom are the uncharged particles within the nucleus.
Isotopy is the existence of two or more atoms of the same element having the same atomic number but having different mass number due to the differences in the number of neutrons in their various nuclei.
Therefore, isotopes differs based on the number of neutrons they contain.
Answer:
D. number of neutrons
Explanation:
Two isotopes of the same element have the same number of protons in the nucleus, but differ in the number of neutrons. The nucleon number is equal to the total number of protons and neutrons in the nucleus. ... The atomic mass number A is equal to the total number of protons and neutrons.
Approximately what percentage of a human's DNA is used for coding Information for the synthesis of proteins?
O 5%
O 25%
О 99%
O 95%
One percent of a human's DNA is used for coding Information for the synthesis of proteins.
What is DNA?
DNA is a hereditary material which is present in human beings as well as all other living organisms. Every cell which is present in an organism's body has DNA which is the same. Most of the DNA is situated in the cell's nucleus and small amount of it can be found in the cell's mitochondria as well.
Information which is stored in DNA is stored as codes made up of four chemical bases namely, adenine, thymine , cytosine and guanine.Human DNA consists of 3 billion bases .The order of the bases determines information which is required for building and maintaining an organism.
DNA bases are capable of pairing up with each other. Adenine pairs with thymine and guanine pairs up with cytosine .Each base is also attached to a sugar molecule and a phosphate group. A base, phosphate sugar are together called as nucleotides.
Learn more about DNA,here:
https://brainly.com/question/30006059
#SPJ6
Your question is incomplete, but most probably your full question was,approximately what percentage of a human's DNA is used for coding Information for the synthesis of proteins?
5%
25%
99%
95%
1%
why sometimes the electrons of an atom transfer to higher energy level
Answer:
According to Bohr, the amount of energy needed to move an electron from one zone to another is a fixed, finite amount. ... The electron with its extra packet of energy becomes excited, and promptly moves out of its lower energy level and takes up a position in a higher energy level. This situation is unstable, however.
The pressure of a sample of helium in a 200. ml. container is 2.0 atm. If the 5 points
helium is compressed toa volume of 10 ml without changing the
temperature, what would be the pressure of the gas? *
4000 atm
1000 atm
40 atm
0.1 atm
The pressure of the gas = 40 atm
Further explanationGiven
200 ml container
P = 2 atm
final volume = 10 ml
Required
Final pressure
Solution
Boyle's Law
At a fixed temperature, the gas volume is inversely proportional to the pressure applied
[tex]\tt \rm p_1V_1=p_2.V_2\\\\\dfrac{p_1}{p_2}=\dfrac{V_2}{V_1}[/tex]
Input the value :
P₂ = P₁V₁/V₂
P₂ = 2 x 200 / 10
P₂ = 40 atm
The theory of _______ of matter states that cannot be created or destoryed
Word bank: Matter Volume Element Conservation Mass Atoms Properties
Answer:
mass pic is explanation hope it helps
Which of the following requires more energy then they produce?
Exothermic
Endothermic
(the subject is science but it wasn’t an option)
Answer:
The answer is endothermic
What is the kinetic energy of a 9 kg object moving at a velocity of 5 m/s?
Is my answer correct?? Please correct me
Thank you!
Answer:
you are right
Explanation:
What type of chemical reaction is the following reaction:
carbon monoxide and oxygen yield carbon dioxide
Answer:
decomposition reaction
Carbon Tetrahydride reacts with Oxygen gas to form Carbon Dioxide gas and Dihydrogen Monoxide gas.
Explanation:
Which element has the larger ionization energy element E or Element M???
Answer: helium has the largest first ionization energy, while francium has one of the lowest.
Explanation:
The ionization energy decreases from top to bottom in groups, and increases from left to right across a period. Thus, helium has the largest first ionization energy, while francium has one of the lowest.
Answer:
Helium has the highest
Explanation:
Why is biodiversity very important?
Answer: Biodiversity is important to humans for many reasons. ... Ecological life support— biodiversity provides functioning ecosystems that supply oxygen, clean air and water, pollination of plants, pest control, wastewater treatment and many ecosystem services.
Explanation:
Which two subatomic particles have an equal, but opposite charge?
Answer:
Electrons have a negative charge. The charge on the proton and electron are exactly the same size but opposite. Neutrons have no charge. Since opposite charges attract, protons and electrons attract each other.Hope that helps
Explanation:
Do the reactants or products contain more energy in the
decomposition reaction of sodium azide?
Answer:
reactants contain more energy in the decomposition reaction of sodium azide?
Explanation:
What mass of oxygen combines with 2.81 mol
of magnesium in the reaction
2 Mg(s) + O2(g) → 2 MgO(s)?
22.48 g. mass of oxygen combines with 2.81 mol of magnesium in the reaction. For the reaction 2 Mg(s) + O2(g) → 2 MgO(s).
What do you mean by molar mass ?The term molar mass is defined as the mass of 1 mole of that particular substance and number of grams per mole of a compound.
In other words, the molar mass is the total mass in grams of all the atoms that make up a mole of a specific molecule. As a result, the molar mass units are grams/mole.
The balance chemical equation is as follows :
2 Mg(s) + O2(g) → 2 MgO(s)
The metal Mg reacts with Oxygen in a 2:1 ratio you would divide 2.81 by two.
Now, we get,
2.81 / 2 = 1.405
You would then multiply 1.405 by the molar mass of Oxygen which is 15.999
= 1.405 × 16
= 22.48 g.
Thus, 22.48 g. mass of oxygen combines with 2.81 mol of magnesium in the reaction.
To learn more about the molar mass, follow the link;
https://brainly.com/question/12127540
#SPJ2
please answer this for me shehsh
Answer:
ih2706
Explanation:
Calculate the vapor pressure (in torr) of a 35°C solution of ethanol and propanol where the mole fraction of propanol is .75.
Assume ideal behavior.
P°ethanol = 100 torr
P°propanol = 36 torr
Answer:
i wish i know
Explanation:
Select the correct answer.
Which statement best describes how chemical equations demonstrate conservation of mass?
A.
The number of reactants is the same as the number of products.
B.
The compounds are the same on each side of the reaction.
C.
The number of atoms of each element is the same on each side of the equation.
D.
The state of matter is the same on each side of the equation.
Answer:
All of the Above
A.The number of reactants is the same as the number of products.
B.The compounds are the same on each side of the reaction.
C.The number of atoms of each element is the same on each side of the equation.
D.The state of matter is the same on each side of the equation.
Explanation:
Answer:
C
Explanation:
I did the test
What unit is used to measure weight?
Answer:
The unit is: Newton.
Hope it helps:D