Answer:
-800 kJ/mol
Explanation:
To solve the problem, we have to express the enthalpy of combustion (ΔHc) in kJ per mole (kJ/mol).
First, we have to calculate the moles of methane (CH₄) there are in 2.50 g of substance. For this, we divide the mass into the molecular weight Mw) of CH₄:
Mw(CH₄) = 12 g/mol C + (1 g/mol H x 4) = 16 g/mol
moles CH₄ = mass CH₄/Mw(CH₄)= 2.50 g/(16 g/mol) = 0.15625 mol CH₄
Now, we divide the heat released into the moles of CH₄ to obtain the enthalpy per mole of CH₄:
ΔHc = heat/mol CH₄ = 125 kJ/(0.15625 mol) = 800 kJ/mol
Therefore, the enthalpy of combustion of methane is -800 kJ/mol (the minus sign indicated that the heat is released).
Which of the following is not part of an amino acid?
A. ammonium group
B. carboxylate group
C. ether group
D. unique "R" group
Answer:
C
Explanation:
Ether group does not exist in amino acids
Ammonium group is on one side
the carboxylate group is opposite to the ammonium group
the R group defines what amino acid it is.
A candle is placed between a concave mirror and its focal point.
Which two of the following best describe the image?
O A. Enlarged
B. Virtual
C. Reduced
D. Real
Virtual and enlarged..............
What grade are you in btw ?
How many grams of O2 are reacted when 3.5
mols of P203 are formed?
What is the molarity of a NaOH solution when 22.14 mL of 0.105 M oxalic acid is needed to
neutralize 25.0 mL of the base.
The molarity of the NaOH solution required for the reaction is 0.186 M
We'll begin by writing the balanced equation for the reaction
H₂C₂O₄ +2NaOH —> Na₂C₂O₄ + 2H₂O
From the balanced equation above,
The mole ratio of the acid, H₂C₂O₄ (nA) = 1
The mole ratio of the base, NaOH (nB) = 2
From the question given above, the following data were obtained:
Volume of the acid, H₂C₂O₄ (Va) = 22.14 mL
Molarity of the acid, H₂C₂O₄ (Ma) = 0.105 M
Volume of the base, NaOH (Vb) = 25 mL
Molarity of the base, NaOH (Mb) =?MaVa / MbVb = nA/nB
(0.105 × 22.14) / (Mb × 25) = 1/2
2.3247 / (Mb × 25) = 1/2
Cross multiply
Mb × 25 = 2.3247 × 2
Mb × 25 = 4.6494
Divide both side by 25
Mb = 4.6494 / 25
Mb = 0.186 MTherefore, the molarity of the base, NaOH solution is 0.186 M
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Which functional group is within the compound shown below?
Which functional group does the molecule below have?
Answer:
B
Explanation:
We can see here that the functional group that the molecule have is: B. Carbonyl
What is a functional group?A functional group is a specific group of atoms or bonds within a molecule that is responsible for the characteristic chemical reactions and properties of that molecule. Functional groups are the parts of organic molecules that determine their reactivity and the types of chemical reactions they can undergo.
In organic chemistry, functional groups play a crucial role in understanding the structure and behavior of molecules. Different functional groups confer distinct properties to molecules, influencing their physical properties, solubility, acidity or basicity, and interactions with other molecules.
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Draw and Name the Cis- isomer for the following compound:
CH3 - CH = CH - CH2 - CH3
Answer:
Cis-2-pentene or Z-2-pentene
What is the pressure of a 1.0 L flask containing 0.12 g of He at 25°C? (R= 0.0821 L atm/mol K)
Answer:
The pressure of the flask is 0.73 atm.
Explanation:
To solve this question, we should use the ideal gas law: PV=nRT, where P represents the pressure (in atm in this case), V represents the volume (in L), n represents the number of moles of gas, R is the ideal gas constant, and T represents the temperature (in K).
Before we can plug our values into the equation, we must convert so that our units cancel out. First, we should convert our temperature from degrees Celsius to degrees K.
25°C + 273.15 = 298.15K
Next, we should convert the 0.12 g He to moles using the molar mass of He.
0.12 g He * (1 mole He/4.003 g He) = 0.029978 mol He
Now, we can plug in the values into the equation and solve for the pressure.
PV = nRT
P = (nRT)/V
P = (0.029978 mol He * 0.0821 L*atm/mol*K * 298.15 K)/(1.0 L)
P = 0.73 atm
Therefore, the correct answer is 0.73 atm.
Hope this helps!
The frequency light of 3.52*10-7
Answer:
The speed of light, c, equals the wavelength, λ (pronounced lambda), times the frequency, ν, (pronounced noo).
c=λν
c is a constant. It is usually given as 3.00×108 m/s or 3.00×1010 cm/s rounded to three significant figures.❤
11) What volume will 0.75 mol of Oxygen gas (O2) occupy at 298 K and a pressure of 52.7 kPa?
Answer:
Volume = 35.3L
Explanation:
Use Ideal Gas Law (PV=nRT) and isolate for V (volume) by dividing both sides by P (pressure). You will then get the eqaution listed below and you can solve by using the method I used below.
V = nRT/P
V = (0.75kPa)(8.314)(298K)/(52.7kPa)
V = 1858.179/52.7
V = 35.3L
How are all atoms of silver alike, but different from atoms of other elements?
A. All atoms of silver have the same mass.
B. All atoms of silver have the same atomic number,
C. All atoms of silver have the same number of neutrons.
D. All atoms of silver have the same number of subatomic particles.
B. All atoms of silver have the same atomic number but different numbers of neutrons in the nucleus.
Which type of energy uses the photoelectric effect?
Biomass
Solar
Geothermal
Wind
Answer:
My lovely people the answer is SOLAR
Explanation:
i just know
The type of energy that uses the photoelectric effect is solar energy. Therefore, the correct option is option B.
When light strikes a material surface, the photoelectric effect takes place, which results in the emission of electrons. Albert Einstein made this intriguing discovery in 1905, and it was essential in the development of quantum physics and our comprehension of the nature of light. The fundamental principle underlying the photoelectric effect is that light is made up of small energy packets known as photons. A photon's energy can be transferred to an electron in a solid or atom when it interacts with those structures. The type of energy that uses the photoelectric effect is solar energy.
Therefore, the correct option is option B.
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A cell phone manufacturer recalled some 50 million lithium batteries installed in cell phones because the batteries were at risk of overheating and exploding. The hazardous waste characteristic of the batteries in this example is __________.
Answer:
universal waste
hope it helps
Of the following, ________ is the most volatile. Select one: C2F6 C2H6 C2I6 C2Cl6 C2Br6
Answer:
C2Br6
because bromine is a liquid volatile
According to the forces of attraction and boiling point C₂Br₆ is most volatile as its boiling point is very low.
What are forces of attraction?Forces of attraction is a force by which atoms in a molecule combine. it is basically an attractive force in nature. It can act between an ion and an atom as well.It varies for different states of matter that is solids, liquids and gases.
The forces of attraction are maximum in solids as the molecules present in solid are tightly held while it is minimum in gases as the molecules are far apart . The forces of attraction in liquids is intermediate of solids and gases.
The physical properties such as melting point, boiling point, density are all dependent on forces of attraction which exists in the substances.
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What can a scientist use to observe very small things?
1. A good pair of glasses
2. Tools and technology
3. The five senses
4. Sense of touch
Answer:
2
Explanation:
depends on how small but you wouldn't be able to see with good glasses your senses or your touch
Answer:
Tools and Technology ( Microscopes etc)
Explanation:
Glasses are not good enough to see on the molecular and cellular level.
The five senses aren't reliable and can vary between people.
Touch is one of the 5 senses, and touching chemicals isn't good.
Determine the frequency of light with a wavelength of 2.672 x 10^-7cm
Answer:
Determine the frequency of light with a wavelength of 2.775⋅10−7 cm. Answer in units of Hz?❤
using the formula F=ma, what force is required to accelerate a car weighing 642 kg at 13 m/s2
REALLY NEED HELP RN
HELP ME ?
PLEASE!??
Answer:
8,346 kmxm/s2
Explanation:
this is physics not chem but you just multiply 13 by 642 to get 8,346. also I'm sorry but it's easy
a meter is defined as 100. cm. How many significant digits are there in the value
Answer:
3 significant figure
Explanation:
Trailing zeros in a number are significant ONLY is the number contains a decimal point.
So if it was 100cm with out the decimal point would only have 1 significant figure.
dubnium chloride chemical formula
Answer:
Db
Dubnium/Symbol
Explanation:
please mark my answer in brainlist plz
Answer:
DbCl5
Explanation
Dubnium has 2 electron in 7s orbital and 3 electron in 6d orbital. Because Dubnium is synthetically produced with atomic number of 105, it is highly radioactive and quickly decay. Like other transition, it can have different oxidation state and it is assumed that dubnium have +3,+4,+5 oxidation state number(that most likely involves electron from 6d orbital). Hence chloride ions with -1 oxidation number would react to form Dubnium Chloride as DbCl3, DbCl4, and DbCl5. Now it is highly unlikely these compounds can really be formed. However if you read nature chemistry article https://www.nature.com/articles/nchem.2610, there is mention that DbCl5, DbBr5, and DbOCl3 may be expected to form.
What types of orbitals are found in the third energy level?
Answer:
1 s-orbital, 3 p-orbital and 5 d-orbital
Answer:
there are a total of nine orbitals in a third energy level
Explanation:
periodicity in chemical properties is based on atomic structure." explain.
Answer:
Periodicity is caused by regular and predictable variations in element atomic structure. ... The rows in the periodic table (the periods) reflect the filling of electrons shells around the nucleus, so when a new row begins, the elements stack on top of each other with similar please help me rank up
Periodicity means the repeating trends in properties of elements in a regular interval. Precocity in chemical properties depends on the atomic structure because, the size, number of electrons, etc affects their reactivity.
What is periodicity?Periodicity is the repetition in in trends in properties after a regular interval. In periodic table, all the elements are classified into different groups and periods.
Groups are vertical columns containing elements of same number of valence electrons and similar chemical and physical properties. Periods are horizontal rows where elements are arranges in the increasing order of atomic number.
Along a period the atomic size decreases, ionization energy and electronegativity increases. But down a group just the reverse for this happens.
In a chemical reaction only valence electrons are participating and the size and number of valence electrons etc affects the chemical reactivity of elements. That's why it is said like periodicity in chemical properties is based on the atomic structure.
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If there is a name/surname you can't make out due to a speaker's manner of speech, what are you supposed to do?
We can call a person by the word gentleman and Sir or from his/her real name.
If there is a name/surname you can't make out due to a speaker's manner of speech then I will call him gentleman or Sir or I will ask him his real name. Gentleman is a word that is used for noble person and Sir word is also used in order to give someone respect.
Call a person with his real name is also comes under the manner of speech so we can conclude that we can call a person by the word gentleman and Sir or from his/her real name.
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Which element represents magnetic properties?
Answer:Demagnetizing a magnet is also possible. Only a few substances are ferromagnetic; the most common ones are iron, cobalt and nickel and their alloys. The rare-earth metals neodymium and samarium are less common examples.
Explanation;
List the four quantum numbers
Answer: In atoms, there are a total of four quantum numbers: the principal quantum number (n), the orbital angular momentum quantum number (l), the magnetic quantum number (ml), and the electron spin quantum number (ms).
Answer:
(n)
(i)
(mı)
(ms) s is suppose to be smaller than the m
Explanation:
the principal quantum number (n)
the orbital angular momentum quantum number (I)
the magnetic quantum number (ml)
the electronic spin quantum number (ms)
I NEED HELP ASAP !!!!
Answer:
5)A &D 6)B
Explanation:
Mass of Fe is 55.845 u
Mass of Cl is 35.453 u
And their sum is 91.298 u
major classification of crude product
pls mark as brainlist
Explanation:
Crude is classified, based on density, as light, medium, heavy, or extra heavy. It can also be classified, based on sulfur content, into a sour and sweet category.
C= ( F - 32) / 1.8
86 F = ?
Answer:
C = 30
Explanation:
C = (86 - 32)/1.8
C = (54)/1.8
C = 30
describe the components of a molecule whose atoms are joined by covalent bonds.
Answer:
nonmetal
Explanation:
In a covalent bond, the atoms bond by sharing electrons. Covalent bonds usually occur between nonmetals. For example, in water (H2O) each hydrogen (H) and oxygen (O) share a pair of electrons to make a molecule of two hydrogen atoms single bonded to a single oxygen atom.
Give reason. When the tip of a plant is cut, it does not grow tall.
Answer: The growth of the plant decides on the presence of plant hormone, auxin which develops in the roots and shoots. Auxins change the rate of elongation in plant cells, controlling how long they become. So, if the tips are removed, there is no auxin made and growth of the plant stops.
Which example accurately describes a solution? (1 point)
Nonpolar oil molecules dissolve in water, which is polar.
Polar sugar molecules dissolve in water, which is polar.
Nonpolar fat molecules dissolve in water, which is polar.
Polar sugar molecules dissolve in oil, which is nonpolar.
The example which accurately describes a solution is; Polar sugar molecules dissolve in water, which is polar.
According to the question:
We are required to determine Which example accurately describes a solution.The formation of a solution requires that the solvent and solute be of the same polarity.
In essence, the example which accurately describes a solution is; Polar sugar molecules dissolve in water, which is polar.
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Answer:
Polar sugar molecules dissolve in water, which is polar.
Explanation:
I did the Exam and got it right!
