Answer:
Explanation:
There is no way to measure the absolute value of the enthalpy of a substance. Only values relative to an arbitrary reference can be determined.
The reference point for all enthalpy expressions is called the standard enthalpy of formation (ΔHºf). Substances are said to be in the standard state at 1 atm, hence the term “standard enthalpy.” The superscript “°” represents standard-state conditions (1 atm), and the subscript “f” stands for formation. By convention, the standard enthalpy of formation of any element in its most stable form is zero.
For instance, molecular oxygen (O₂) is more stable than the other allotropic form of oxygen, ozone (O₃), at 1 atm and 25°C. Thus, we can write ΔHºf (O₂) 5 0, but ΔHºf (O₃) 5 142.2 kJ/mol.
Based on this reference for elements, we can define the standard enthalpy of formation of a compound as the heat change that results when 1 mole of the compound is formed from its elements at a pressure of 1 atm.
Answer:
This is the enthalpy change that occurs when a compound is formed from its component elements.
Explanation:
This is the enthalpy change that occurs when a compound is formed from its component elements.
Do you know the three core principles of cell theory?
All living organisms are composed of one or more cells. The cell is the basic unit of structure and organization in organisms. Cells arise from pre-existing cells.
Which metal most likely conducts electricity best aluminum or copper
Answer: Copper
Explanation: did it on Edgenuity 2020
Answer:
first is copper
second is gold
(2 x 109) x (5 x 105).
Answer:
114450
Explanation:
2*109 = 218
5*105 = 525
218*525 = 114450
Select the descriptor (A, B, C, D): that best describes the relationship between the reactants and products below: Reactant ProductCH3CH3OH + H2O A B C D CH3CH2O^- + H3O^+
Answer:
A- conjugate acid
B- conjugate base
C- conjugate base
D- conjugate acid
Explanation:
According to the Brownstead-Lowry definition of acids, an acid donates a proton while a base accepts the proton.
If we look at the species ABCD, species A and D donate protons while species B and C accept protons.
C is the conjugate base of A while D is the conjugate acid of B, hence the answer.
what is true that if at the same temperature 2 objects have equal masses, but different densities
Answer:
The two objects have different volumes.
Explanation:
The density of an object measures how closely packed the mass in the object is. Density of an object is obtained by taking the ratio of the mass of an object and its volume.
Density = mass/volume
The mass present in an object is constant, but the volume may vary with temperature. The volume of substances generally increases with temperature, therefore, density decreases with increase in volume.
Two objects at the same temperature having equal masses may or may not have the same density depending on the volume each object occupy.
If two substances are at the same temperature and have equal masses but different densities, then they must have different volumes.
A chemist must prepare of hydrobromic acid solution with a pH of at . He will do this in three steps: Fill a volumetric flask about halfway with distilled water. Measure out a small volume of concentrated () stock hydrobromic acid solution and add it to the flask. Fill the flask to the mark with distilled water. Calculate the volume of concentrated hydrobromic acid that the chemist must measure out in the second step. Round your answer to significant digits.
Hello. This question is incomplete. The full question is:
A chemist must prepare 500.0mL of hydrobromic acid solution with a pH of 0.50 at 25°C. He will do this in three steps: Fill a 500.0mL volumetric flask about halfway with distilled water. Measure out a small volume of concentrated (5.0M) stock hydrobromic acid solution and add it to the flask. Fill the flask to the mark with distilled water. Calculate the volume of concentrated hydrobromic acid that the chemist must measure out in the second step. Round your answer to significant digits.
Answer:
31.62 mL
Explanation:
To achieve this result, you must start by calculating the H + concentration. You will do this using the following formula:
pH = -log [H +]
0.50 = -log [H +]
[H +] = 10 ^ -0.50
[H +] = 0.31623 mol / L
After that you must consider that hydrobromic acid will have a weak capacity to disassociate, since it has a strong nature. In this case, we can consider that [HBr] = [H +] = 0.31623 mol / L.
After reaching this reason, it is necessary that you dilute the stock solution, using the formula:
C1V1 = C2V2
5.0 * V1 = 0.31623 * 500.0
V1 = 31.62 mL
And so you finish the answer.
Which statement accurately describes the Doppler effect?
Answer:
Explanation:
These statements accurately describe the Doppler Effect: It indicates galaxy motion through light wavelengths. It indicates a galaxy moving toward Earth through red shift. I hope this helps.
The pKs of succinic acid are 4.21 and 5.64. How many grams of monosodium succinate (FW = 140 g/mol) and disodium succinate (FW = 162 g/mol) must be added to 1 L of water to produce a solution with a pH 5.28 and a total solute concentration of 100 mM? (Assume the total volume remains 1 liter, answer in grams monosodium succinate, grams disodium succinate, respectively.)
Answer:
9.744g of monosodium succinate.
4.925g of disodium succinate.
Explanation:
To find pH of the buffer produced by the mixture of monosodium succinate-Disodium succinate is obtained from H-H equation:
pH = pKa + log ([Na₂Suc] / [NaHSuc])
As you want a pH of 5.28 and pKa is 5.64:
5.28 = 5.64 + log ([Na₂Suc] / [NaHSuc])
-0.36 = log ([Na₂Suc] / [NaHSuc])
0.4365 = ([Na₂Suc] / [NaHSuc]) (1)
As total concentration of the buffer is 100mM = 0.100M:
0.100M = [Na₂Suc] + [NaHSuc] (2)
Replacing (2) in (1):
0.4365 = (0.100M - [NaHSuc] / [NaHSuc])
0.4365 = (0.100M - [NaHSuc] / [NaHSuc])
0.4365 [NaHSuc] = 0.100M - [NaHSuc]
1.4365 [NaHSuc] = 0.100M
[NaHSuc] = 0.0696M
And:
[Na₂Suc] = 0.0304M
As volume of the buffer is 1L:
[NaHSuc] = 0.0696 moles
[Na₂Suc] = 0.0304 moles
Using molar mass of both substances:
Mass of monosodium succinate:
0.0696moles * (140g / 1mol) = 9.744g of monosodium succinate.
Mass of disodium succinate:
0.0304moles * (162g / 1mol) = 4.925g of disodium succinate.
The periodic table of elements is organized by the number of
Answer:
the increasing mass number
The prefix 'mili-' means a thousandth,
So a mili-liter is a thousandth of a liter.
1 mililiter = 1/1000 liter
How many liters is 1,979 mililiters
Round your answer to the nearest tenth of a liter,
Will GIVE BRAINLY
Compare atoms and molecules.
Answer: An atom is the sub-component of a molecule, or the smallest unit of matter. It is the smallest part an element can divide into. A molecule is made up of atoms that are bound by ionic, covalent or metallic bond.
Answer:
veryy help ful
Explanation:
An atom is the sub-component of a molecule, or the smallest unit of matter. It is the smallest part an element can divide into. A molecule is made up of atoms that are bound by ionic, covalent or metallic bond.
17. Elements in the periodic table are arranged according to their.
what is the percent composition by mass of benzene?
Answer:
25.0%
A solution of benzene (C6H6) and toluene (C7H8) is 25.0% benzene by mass. At 25 °C the vapor pressures of pure benzene and pure toluene are 94.2 torr and 28.4 torr, respectively.
Write an equation that shows the formation of a sodium ion from a neutral sodium atom.
Answer:
The answer to your question is given below.
Explanation:
Sodium (Na) is a group 1 element because it has 1 electron in it's outermost shell.
Sodium ion (Na+) is formed when sodium atom (Na) lose it's outermost electron to attain the octet configuration of the noble gas element.
This can further be seen from the equation given below:
Na —> Na+ + e
Thus, we can represent the above in electronic configuration form as follow:
Na (11) => 1s² 2s²2p⁶ 3s¹
Na+ (10) => 1s² 2s²2p⁶
An air bubble at the bottom of lake with temperature 7 0C and pressure of 3.2 atm has a radius of 2.5 cm. It rises to the surface where the temperature is 25 oC and atmospheric pressure is 1 atm. What is the volume of the bubble at the surface? Assume perfect gases. V=(4/3)πr3.
Answer:
[tex]2.0 \times 10^{2} cm^{3}[/tex]
Explanation:
Step 1: Given data
Initial pressure (P₁): 3.2 atmInitial temperature (T₁): 7 °C = 305 KInitial radius (r₁): 2.5 cmFinal pressure (P₂): 1 atmFinal temperature (T₂): 25 °C = 298 KFinal volume (V₂): ?Step 2: Calculate the initial volume
We will use the following expression.
V = 4/3 × π × r³
V = 4/3 × π × (2.5 cm)³
V = 65 cm³
Step 3: Calculate the final volume
Assuming ideal behavior, we can calculate the final volume of the bubble using the combined gas law.
[tex]\frac{P_1 \times V_1 }{T_1} = \frac{P_2 \times V_2 }{T_2}\\V_2 = \frac{P_1 \times V_1 \times T_2 }{T_1 \times P_2} = \frac{3.2atm \times 65cm^{3} \times 298K }{305K \times 1atm} = 2.0 \times 10^{2} cm^{3}[/tex]
Solve each of the following problems using one or more conver-sion factors:a. A container holds 0.500 qt of liquid. How many milliliters of lemonade will it hold?b. What is the mass, in kilograms, of a person who weighs 175lb?c. An athlete has 15% body fat by mass. What is the weight of fat, in pounds, of a 74-kg athlete?d. A plant fertilizer contains 15% nitrogen (N) by mass. In a container of soluble plant food, there are 10.0 oz of fertilizer. How many grams of nitrogen are in the container?
Answer:
a. 473mL.
b. 79.38kg
c. 24.47lb of fat
d. 42.5g of N.
Explanation:
a. A qt is equal to 946mL. 0.500qt are:
0.500qt * (946mL / 1qt) = 473mL
b. 1lb is equal to 0.4536kg, 175lb are:
175lb *(0.4536kg / 1lb) = 79.38kg
c. The fat in kg of the athlete is:
74kg * 15% = 11.1kg of fat. In pounds:
11.1kg * (1lb / 0.4536kg) = 24.47lb of fat
d. The mass of nitrogen in the fertilizer is:
10.0oz * 15% = 1.5oz of N
1 oz is equal to 28.35g. 1.5oz are:
1.5oz * (28.35g / 1oz) = 42.5g of N
A solution contains 3.95 g of carbon disulfide (CS2, molar mass = 76.13 g/mol) and 2.43 g of acetone ((CH3)2CO, molar mass = 58.08 g/mol). The vapor pressure of pure carbon disulfide and acetone at 35 o C are 515 torr and 332 torr, respectively. Assuming ideal solution behavior, calculate the vapor pressure of each of the components and the total vapor pressure above the solution. The total vapor pressure above the solution at 35 o C was experimentally determined to be 645 torr. Is the solution ideal? If not, indicate whether the solution deviates from Raoult’s law in a positive or negative manner
Answer:
The solution is not ideal and shows a positive deviation from Raoult’s law since Psolution (experimental) > Psolution (actual).
Explanation:
Number of moles of CS2 = 3.95g/76.13gmol-1 = 0.0519 moles
Number of moles of acetone = 2.43g/58.08gmol-1 = 0.0418 moles
Total number of moles = 0.0937 moles
Mole fraction of CS2 = 0.0519/0.0937 = 0.5538
Mole fraction of acetone = 0.0418/0.0937 = 0.4461
From Raoult’s law;
PCS2 = 0.5538 × 515 torr = 285.207 torr
Pacetone = 0.4461 × 332 torr = 148.1052 torr
Total pressure = 285.207 torr + 148.1052 torr = 433.3 torr
Which of the following describes radioactive decay by beta particle emission?a. The daughter isotope has an atomic number two less than the parent and a mass number four less.b. The mass number of the daughter isotope is one more than the parent, and both isotopes have the same atomic number.c. The atomic number of the daughter isotope is one more than the parent; the mass numbers are the same.d. The daughter isotope has an atomic number one less than the parent and a mass number two less.
Answer:
c. The atomic number of the daughter isotope is one more than the parent; the mass numbers are the same
Explanation:
Radioactive decay by beta particle emission involves the emission of an electron.
An electron is a very light particle and its emission does not reflect a loss in mass of the parent molecule. However, the atomic number of the parent molecule increase by one due to the retention of a proton.
Therefore, the daughter isotope has the same mass number as the parent molecule but its atomic number increases by one unit.
An example of beta particle emission is given below;
Th₀(234) ---> Pa₉₁(234) + e₋₁(0)
Thorium₉₀(234) emits a beta particle, e₋₁(0) to give Protactinium₉₁(234)
Answer:
c
Explanation:
100 POINTS!! PLEASE HELP WILL MARK BRAINLIEST
Answer:
a. 13.5 mL
b. 4.01 g and 112.0 mL
c. 22.3 mL
d. 2.62 g/mL
e. it will float on bromine and mercury
Explanation:
a. 13.534=10/x
b. 8.920=x/0.45 and 8.920= 1000/x. the reason its 1000 is because 1 kg is converted to grams, same unit for the density.
c. 0.789=17.6/x
d. 68.2-56.3 is the volume of the quartz. so 31.18/11.9 is the density
e. 33.93/12.5 gives you the density which is 2.7144. so in order to float, it has to be in a substance with a greater density such as bromine with a 3.119 density.
Hope that helped!
I need help with this please
Answer:
Not sure ask Estellia
Explanation:
Answer:
h= 4.9
Explanation:
l x w x h = a
7.66 x 3.75 x h = 141
28.725h = 141
Divide both sides by 28.725 to solve for h.
Ok, so I'm learning about mass and volume and density.
I'm confused about this research card I'm doing.
Alright, if the mass is greater than the volume the object should sink in the liquid. right?
Object 9- mass=99.0 Volume=44.0 and it sinks. Density=.222
please someone explain why it sunk when the volume is greater than the mass.
(for comparison purposes).
Object 10- Mass 42.0 Volume 461.0 and it floats. density is .090
please help me .-.
Answer:
I believe it's because density is how dense something is. So even if the volume(how much space it takes up in an object) is greater, if the densitity of the object is greater then the density of the water it will sink.
Explanation:
The basic principle in balancing a chemical equation is to ______. View Available Hint(s) The basic principle in balancing a chemical equation is to ______. have the sum of coefficients in reactants equal to that in the products have the same number of atoms of each element in the reactants and in the products have the same number of reactants as products have the same number of molecules of each substance in the reactants and in the products
Answer:
have the same number of atoms of each element in the reactants and in the products
Explanation:
The basic principle in balancing a chemical equation would simply be to have the same number of atoms of each element in the reactants and in the products.
A balanced chemical equation is one that has the same number of atoms of each element on the reactant and the product's side of the equation. For example, consider the equation below:
[tex]H_2 + O_2 --> H_2O[/tex]
On the reactant's side, there are 2 atoms of H and O while there are 2 atoms of H and 1 atom of O on the product's side. This is an imbalanced equation. In order for it to be balanced, the number of atoms of H and O on the reactant side must be equal to the number of H and O on the product side as below.
[tex]2H_2 + O_2 --> 2H_2O[/tex]
The boiling points of some of the unknown will be difficult to measure using the procedure described. identify the liquids that will pose a problem and explain why?
Answer:
Methyl Alcohol.
Acetate
Heptane
Dioxane
Explanation:
The boiling point of liquids are measure by observing the gas pressure or vapors temperature. There are few liquids whose boiling point is difficult to measure. The gas pressure differs for every liquid. It is important to observe the vapor pressure also to identify the boiling point. The most difficult boiling point identification is for Methyl alcohol as it has ability to absorb different level of pressure.
The liquids are Methyl Alcohol, Acetate, Heptane,Dioxane
Information regarding the liquids:
The boiling point of liquids should be determined by watching the gas pressure or vapors temperature. There are few liquids whose boiling point is difficult to calculate. The gas pressure should be different for every liquid. The most difficult boiling point identification is for Methyl alcohol because it has ability to absorb different level of pressure.Find out more information about the pressure here: https://brainly.com/question/356585?referrer=searchResults
d
1.123 L
Question 7 (1 point)
Conversion Factors:
1 tsp = 5 mL
1 quart - 0.946 L
1 cup 48 tsp
1 tbsp = 3 tsp
1 ml. = 7 drops
1 L=1000 ml
1 cup - 110 g
1 kg = 1000 g
1 gallon = 4 quarts
1 cm 1 mL
1 cup - 200 ml
1 m = 1,000,000 cm
How many grams are in 4.78 cups?
са
b
0.043 8
5258 g
114.78 g
4.78 g
oc
od
Answer:
can you provide a picture?
A gold-colored pebble is found in a stream. Its mass is 23.2 mg and its volume is 1.20 mm3. What is its density in grams per cubic centimeter? Is it gold?
Answer:
The density in g/cm3 is 1.9333(put a line above the 3's to show it's repeating).
And no it is not gold because the density of gold in g/cm3 is 19.3.
Explanation:
Divide the mass by the volume in order to get an object's Density.
so, 23.2 divided by 1.20 mm3
=1.93333333 g/cm3
That is the density then you find out the density of gold in grams per cubic centimeter, that is 19.3 g/cm3
For example, gold will always have a density of 19.3 g/cm3; if a mineral has a density other than that, it isn't gold.
Which expression correctly describes energy using SI units? A. 1 J=1kg•m^2/s^2 B. 1 J= 1kg•m/s^2 C. 1 J= 1kg• m/s D. 1 J= 1kg•m^2/s
Answer:
A. 1 J=1kg•m^2/s^2
Explanation:
Energy refers to the capacity to do work. According to the International System of units (SI units), energy is measured in Joules.
Energy is represented by the force applied over a distance. Force is measured in Newton (N) and distance in metres (m). Hence, energy is Newton × metre (N.m)
Newton is derived from the SI units of mass (Kilograms), and acceleration (metres per seconds^2) i.e Kg.m/s^2, since Force = mass × acceleration.
Since; Energy = Newton × metres
If Newton = Kg.m/s^2 and metres = m
Energy (J) will therefore be; Kg.m/s^2 × m
1J = Kg.m^2/s^2
2.
Question: How much water is best for a pea plant to grow?
Answer:
Explanation:
Growing Peas
Planting depth should be roughly 2 inches with a spacing of about 2 inches apart. Water well at planting and provide at least 1 inch of water per week, particularly during the flowering and pod production stages. As the temperature rises, the vines may need to be deeply watered almost every day.
Make sure to moniter it and change the water depending on how dry or overwatered it looks like. :)
Bromine has two isotopes, Br79 and Br81. The isotopes occur in a 50:50 (1:1) ratio. Given that the mass spectrum of bromine contains peaks for both bromine atoms and diatomic bromine molecules, predict the number of peaks in the spectrum. What would be the relative height of the atomic peaks
Answer:
There will be 3 peaks.
Relative height of the atomic peaks would be; 158, 160 and 162
Explanation:
We are told that Bromine has two isotopes namely 79Br and 81Br in a 1 : 1 ratio (50 : 50).
This means that a compound which contains 1 bromine atom will have two peaks in the molecular ion region but it depends on which bromine isotope is contained in the molecular ion.
Thus;
Relative height of atomic peaks is given by;
m/z = 79Br¯ 79Br+ = 158
79Br¯ 81Br+ = 160
81Br¯ 81Br+ = 162
IF YOU ANSWER FIRST, I'll give you the crown hehe
Data can be collected by observations and performing experiments.
True OR False
Answer:
True
Explanation:
Draw the conjugate acid of ethanol
Answer:
H₃O⁺.
Explanation:
Hello,
In this case, ionization of ethanol yields hydrogen cations and ethoxide anions as follows:
[tex]CH_3COOH+H_2O\rightleftharpoons H_3O^++CH_3COO^-[/tex]
Which is at equilibrium as ethanol is a weak acid. Thus, since the conjugate acid is formed by the outgoing H⁺ and the water, we say that the conjugate acid is then the hydroxonium ion, H₃O⁺ whereas the conjugate base is the remaining anion CH₃COO⁻.
Best regards.
