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!
What happens at a constant temperature, as time progresses?
Answers -
1.Phase change
2.Bonding of particles
3.Separation of particles
4.The substance remains in its initial phase
A mole of Br2 and a mole of CH2Br2
Select one:
A. have a mass of 1g each
B. contain the same number of molecules
C. contain one molecule each
D. have the same mass
The term mole is defined as the amount of substance of a system which contains as many elementary entities. A mole of Br₂ and a mole of CH₂Br₂ have a mass of 1g each. Therefore, option A is correct.
What do you mean by mole ?The term mole is defined as the amount of substance of a system which contains as many elementary entities.
1 mole is equal to 6.023 × 10 ²³ molecules.
One mole of any substance is equal to 6.023 × 10²³ units of that substance such as atoms, molecules, or ions. The number 6.023 × 10²³ is called as Avogadro's number or Avogadro's constant.
The mole concept can be used to convert between mass and number of particles.
A mole of Br₂ and a mole of CH₂Br₂ have a mass of 1g each. Because one mole of substance is equal to 6.023 × 10 ²³ molecules.
Thus, option A is correct.
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Describe an every day example of an object that has energy of motion and object that has stored energy
Answer:
Humans
Explanation:
Humans have energy of motion and store energy.
Every object will have any form of energy. For instance, when we are walking we gains a kinetic energy. We use electronic devices where electrical energy is stored and can be converted to mechanical energy to activate any motors.
What is energy transformation?Energy can neither be created nor be destroyed. However it can be transformed to any other forms. Thus, the total energy will conserved always.
We have a lot of example for energy transformation and storage. The energy form stored by virtue of the position of an object is called potential energy. Whereas, when the object starts moving potential energy converts to kinetic energy.
Thus, thermal vibrations of particles, our every day activities all are associated with a kinetic energy. Kinetic energy of each body depends on the mass and velocity of the body. The more the mass and velocity more will be the kinetic energy.
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Substance X is extremely acidic. Substance Y is extremely basic. What would be formed if substance X and Y were mixed together?
Answer:
salt will form bcz when acids reacts with base then it forms salts . and this reaction is called neutralization reaction
What causes the biggest change mass or speed?
Answer:
Explanation if an object is in motion and more force is applied to it, the object will begin moving faster. If two objects have the same mass and a greater force is applied to one of the objects, the object which receives the greater force will change speeds more quickly.:
Answer:
i think that it is F
Explanation:
WILL GIBE BRAINLIEST!!!!!! Think research, and discuss: As you move across a period, you will recall that
the radius decreases. Why do you think a decrease in atomic radius would
result in a greater ionization energy?
(5 Points)
The effective nuclear charge is increasing due to less distance between protons and
neutrons.
O
The effective nuclear charge is increasing due to less distance between protons and
electrons.
The effective nuclear charge is decreasing due to less distance between protons
and neutrons.
The effective nuclear charge is decreasing due to less distance between protons
and electrons.
Highlight the examples of radiation in the passage
below.
A chemist working in the laboratory is
investigating the thermal energy of H2O in a
solid, liquid, and gas state. First, she places
ice in a pan on a burner and heats it. She
records the temperature at which the solid ice
melts. Next she takes the liquid water and
heats it in a microwave. The liquid begins to
bubble and evaporate into a gas. She records
the temperature at which the liquid water
turned into a gas.
Answer:
Heating of the liquid water in a microwave.
Explanation:
Radiation is a form of heat transfer process that does not require a material medium rather it travels through space or vacuum in the form of electromagnetic waves or radiation. Heat transfer by radiation occurs in the form of microwaves, infrared radiation, visible light, or another form of electromagnetic radiation is emitted or absorbed. Some common examples of heat transfer by radiation is the warming of the Earth by the Sun, the warmth one experiences while sitting by the campfire, or the heating up of foods in a microwave.
Black bodies or surfaces are good absorbers as well as emitters of radiation. On the other shiny or white surfaces are poor radiators of heat.
From the above discussion on radiation, it can be seen that when the chemist takes the liquid and heats it in a microwave, the heat absorbed by the liquid to change to gaseous state is transferred through radiation.
You add a neutron to the nucleus of the atom. How many protons, neutrons, and electrons do you have now
number of protons, neutrons, and electrons for an atom of any element. Atoms are made of protons, neutrons, and electrons. Protons carry a positive electrical change, while electrons are negatively charged, and neutrons are neutral.
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PLEASE HELP ME, 20 POINTS
How many atoms are in 25.00 g of Li.
Question 1 options:
2.393 x 1024 atoms of Li
1.333 x 1023 atoms of Li
2.16 x 1026 atoms of Li
2.17 x 1024 atoms of Li
How many grams is 2.393 x 1024 atoms of Cl
Question 2 options:
70.45 g Cl
140.9 g Cl
140.9 mole Cl
70.45 mole Cl
How many atoms are in 25.00 g of B.
Question 3 options:
1.393 x 1024 atoms of B
1.333 x 1023 atoms of B
2.16 x 1026 atoms of B
2.17 x 1024 atoms of B
How many grams is 2.393 x 1024 atoms of O
Question 4 options:
70.45 g O
140.9 g O
63.58 mole O
63.58 g O
Explanations:
Question 1: Lithium in 20.00+ g is C. or D., but 25.00+ g is D. which means this is the correct option.
I am unsure of Question 2. I don't think it is mole though.
Question 3: Boron in 25.00-30.00 g is B. or D., but 25.00 g would be C.
Question 4: 2.393 x 1024 atoms of Oxygen is 63.58 mole O. I don't know for sure, but I think this is correct.
I am NOT professional. There is a chance I am incorrect. Please reply to me if I've made a mistake.
What is the relationship between a front and cloud formation?
Answer:
Weather fronts can cause clouds to form. Fronts occur when two large masses of air collide at the Earth's surface. Warm fronts produce clouds when warm air replaces cold air by sliding above it.
Explanation:
Which of the following best describes the movement of particles in a solid?
O A. Particles can vibrate slightly, but are unable to move around.
O B. Particles move past each other freely.
O C. Particles travel at high speeds in all directions.
O D. Particles travel at low speeds in all directions.
Answer:
A
Explanation:
particles are frozen and hence will vibrate in their fixed positions
Find the mass of 5.60 L O2 at 1.75 atm and 250.0 K
Answer:
Moles O2 = pV/RT = 2.75 x 5.60 / 0.08206 x 250=0.751
mass = 32 g/mol x 0.751 mol= 24.0 g
Explanation:
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The mass of 5.60 Liter oxygen at 1.75 atm pressure and 250.0 K temperature is 24.0 gram.
What is ideal gas equation?
Ideal gas equation is a hypothesis which tells about the behavior of gas at standard condition and it is represented as:
PV = nRT, where
P = pressure = 1.75 atm
V = volume = 5.60 L
R = universal gas constant = 0.0821 L.atm /K.mol
T = temperature = 250 K
n is the moles of gas which will further define as:
n = W/M, where
W = required mass
M = molar mass
Now putting all the value in the above ideal gas equation and calculate for moles as:
n = (1.75)(5.60) / (0.0821)(250)
n = 0.751
Molar mass of oxygen is 32 g/mol and we calculate their required mass as:
W = 32 g/mol x 0.751 mol= 24.0 g
Hence, the required mass of oxygen is 24.0 g.
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is cellphone is made from renewable resources * true or false
Answer:
T
Explanation:
3. How many moles of hydrogen atoms are present in 2.0 moles of ammonia
NH3?
A.3.0 mol
B. 6.0 mol
C. 8.0 mol
D. 2.0 mol
Answer:
3 I think
Explanation:
this could be because I noticed the 3 subscript by the H which is the letter for hydrogen but I'm not 100% sure
if I'm correct, then ur welcome <3 it's always nice to be nice UwU
here's Jay Jay for u cuz I love her ^^
How many Joules of heat are required to melt 250 grams of ice at 0°C?
AHfus = 334 J/g
AHvap = 2258 J/g
Cp= 4.184 J/g C
Heat required : Q = 83500 J = 83.5 kJ
Further explanationGiven
mass ice = 250 g at 0°C
Required
The heat required
Solution
The heat to change the phase can be formulated :
Q = m.Lf (melting/freezing)
Lf=latent heat of fusion
Input the value :
Q = 250 g x 334 J/g
Q = 83500 J
Why don't we feel the air pressing on us all the time?
Answer: Why don't we feel the air pressing on us all the time?
Explanation:
Because air is a fluid, the weight of the air is transmitted to the palm of your hand and to the back of your hand at the same time. These forces cancel so that your hand overall feels no net force
Answer:the gravity in the atmosphere is pulling all the air so we can survive
Explanation:
If I have 5 mols of Neon how many grams of Neon do I have?
Answer:
20.1797 grams.
Explanation:
The molecular formula for Neon is Ne. The SI base unit for amount of substance is the mole. 1 mole is equal to 1 moles Neon, or 20.1797 grams.
A gas has an initial volume of 15L and the pressure is at 2atm. If the temperature increases from 330K to 462K and the pressure reduced to 1 ATM, what is the new volume of the gas?
Answer:
42L
Explanation:
Using the combined gas law equation as follows:
P1V1/T1 = P2V2/T2
Where;
P1 = initial pressure (atm)
P2 = final pressure (atm)
V1 = initial volume (L)
V2 = final volume (L)
T1 = initial temperature (K)
T2 = final temperature (K)
According to the provided information in this question, P1 = 2atm, V1 = 15L, T1 = 330K, T2 = 462K, P2 = 1atm, V2 = ?
Using the formula;
P1V1/T1 = P2V2/T2
2 × 15/330 = 1 × V2/462
30/330 = V2/462
Cross multiply;
462 × 30 = 330 × V2
13860 = 330V2
V2 = 13860 ÷ 330
V2 = 42L
The new volume is 42L
What is the mass of 3.5 mol of MgBr2?
Answer:
The answer is 0.0054314469917931.
Explanation:
I assume you are converting between moles MgBr2 and gram. You can view more details on each measurement unit: molecular weight of MgBr2 or grams This compound is also known as Magnesium Bromide.
How many protons, neutrons, and electrons do the following elements have? Ca, Na, U, Yt
Answer:
Ca- 20,20,20
Na-11,12,11
U-92,146,92
i dont know what the last one is
Explanation:
HELP! URGENTLY NEEDED! I NEED THIS ANSWER IN 5 MINUTES AND PERSON WHO HELPS GET THE ANSWER RIGHT GETS 25 POINTS!!! PLEASE I AM FAILING THIS CLASS AND NEED SO MUCH HELP!!!!
The coefficient/s will balance the chemical equation CH4 +O2 -------» CO2 + H2O is
a
1, 2, 1, 2
b
2, 1, 1, 2
c
2, 2, 1, 1
d
1, 1, 1, 2
Answer:
hey miss
Explanation:
The coefficients : a. 1,2,1,2
Further explanationGiven
Reaction(unbalanced)
CH4 +O2 -------» CO2 + H2O
Required
The blanced equation
Solution
Give a coefficient
CH4 +aO2 -------» bCO2 + cH2O
Make an equation
C, left=1, right=b⇒b=1
H, left=4, right = 2c⇒2c=4⇒c=2
O, left=2a, right=2b+c⇒2a=2b+c⇒2a=2.1+2⇒a=2
The equation becomes :
CH4 +2O2 -------» CO2 + 2H2O
When sodium is placed in cold water does a reaction occur
Can someone help me please. This is the last day
Answer:
atomic nucleus :)
Explanation:
How many moles of each element (C, H, and O) are present in a 100.0 g sample of
ethanol?
Answer:
2.173 moles of ethanol is presented in a 100.0g sample of ethanol .
Explanation:
The amount of substance that contains as many Particles as there are atoms in exactly 12g of carbon- '12 isotope is called 1 mole '= 46 u.
What does the large number in front of
the molecule represent?
What is the name of this formula: Fe3Cl? PLEASE AND THANK YOU :(
Answer:
Ferric Chloride or Iron (III) Chloride
Explanation:
The Independent Variable is:
Kinetic Energy
Height
Mass
Speed
If 10.0 L of nitrogen gas reacts with 16.0 L of hydrogen gas, how many liters of ammonia gas (NH3) will be
produced?
Volume of ammonia gas : 10.67 L
Further explanationGiven
10.0 L of nitrogen gas
16.0 L of hydrogen gas
Required
Volume of ammonia gas
Solution
Reaction
N₂ + 3H₂ ⇒ 2NH₃
From Avogadro's hypothesis, at the same temperature and pressure, the ratio of gas volume will be equal to the ratio of gas moles
Find limiting reactant :
N₂ : 10 : 1 = 10
H₂ : 16 : 3 = 5.3
H₂ as a limiting reactant
So volume of NH₃ based on H₂
= 2/3 x volume H₂
= 2/3 x 16 L
= 10.67 L
is aluminum intensive or extensive
Answer:
Intensive
Explanation:
Aluminium is an Intensive Metal
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What is the relationship of transported particle size to water velocity?
Answer:
The faster the water is flowing, the larger the particles that can be kept in suspension and transported within the flowing water.This is the relationship of transported particle size to water velocityExplanation:
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