Answer:
A) Ca(s) + C(s) + 3/2 O₂(g) → CaCO₃(s)
Explanation:
Standard enthalpy of formation of a chemical is defined as the change in enthalpy durin the formation of 1 mole of the substance from its constituent elements in their standard states.
The consituent elements of calcium carbonate, CaCO₃, in their standard states (States you will find this pure elements in nature), are:
Ca(s), C(s) and O₂(g)
That means, the equation that represents standard enthalpy of CaCO₃ is:
A) Ca(s) + C(s) + 3/2 O₂(g) → CaCO₃(s)Is the equation that has ΔH° = -1207kJ/mol
a flask contains 0.25 naoh. what mass of naoh is present per dm3 of solution
Answer:
30 g 0f NaOH.
Explanation:
The following data were obtained from the question:
Molarity of NaOH = 0.25 M
Volume = 3 dm³
Mass of NaOH =?
Next, we shall determine the number of mole of NaOH present in 3 dm³ of 0.25 M NaOH solution.
This can be obtained as follow:
Molarity of NaOH = 0.25 M
Volume = 3 dm³
Mole of NaOH =?
Molarity = mole /Volume
0.25 = mole of NaOH/3
Cross multiply
Mole of NaOH = 0.25 × 3
Mole of NaOH = 0.75 mole
Finally, we shall determine the mass of NaOH as follow:
Mole of NaOH = 0.75 mole
Molar mass of NaOH = 23 + 16 + 1 = 40 g/mol
Mass of NaOH =.?
Mole = mass /Molar mass
0.75 = mass of NaOH /40
Cross multiply
Mass of NaOH = 0.75 × 40
Mass of NaOH = 30 g
Therefore, 30 g 0f NaOH is present in the flask.
The mass of NaOH in 0.25 M sample has been [tex]\rm\bold{ 30\;g/dm^3}[/tex].
The molarity has been defined as moles of sample present in a liter of solution.
The molarity of given NaOH solution has been 0.25 M. It has been stating that 0.25 moles of NaOH has been present in a liter of solution.
The mass of sample present in 1 cubic decimeter has been the mass of sample in a liter of solution as:
[tex]\rm 1\;dm^3=1\;L[/tex]
The molarity (M) has been given as:
[tex]M=\dfrac{\text {mass}}{mwt}\;\times\;\dfrac{1}{V(L)}[/tex]
Where, the molarity of NaOH sample has been, [tex]M=0.25\;\text M[/tex]
The molar mass of NaOH has been, [tex]mwt=40\;\text {g/mol}[/tex]
The volume of solution has been, [tex]V=3 \;\text L[/tex]
Substituting the values for mass of NaOH:
[tex]0.25=\dfrac{mass}{40}\;\times\;\dfrac{1}{3} \\mass=0.25\;\times\;40\;\times\;3\\mass=30\;\text g[/tex]
The mass of NaOH in 0.25 M sample has been [tex]\rm\bold{ 30\;g/dm^3}[/tex].
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A regular solid measures 13.4 cm x 11.0 cm x 2.2cm. Calculate the volume of the solid.
Answer:
324.28 cm cubed
Explanation:
13.4 cm x 11.0cm x 2.2cm = 324.28 cm cubed
The phase of any substance is dependent upon temperature and pressure.
True
False
Answer:
False
Explanation:
Answer:
false
Explanation:
pressure has nothing to do with the phases of a substance.
Compare the physical properties of two forms of carbon: diamond and graphite
Diamond and graphite are allotropes of carbon and have various differences in their physical properties.
Explanation:
Diamond:
It is crystalline in natureEach Each C is [tex]sp^{3}[/tex] hybridized and forms 4 covalent binds with neighboring C atomsThe geometry is tetrahedralC-C bond length is 154 pmIt has rigid covalent boning which is difficult to break.It acts as an electric insulatorGraphite:
It has layered structureEach C atom is sp2 hybridized and forms 3 sigma bonds with 3 other C atoms. Fourth electron forms pi bond. The geometry is planarC-C bond length is 141.5 pmIt is soft. Its layers can be separated easilyIt is good conductor of electricity.This is the comparison of the physical properties of two forms of carbon: diamond and graphite
Carbon and Diamond are allotropes of carbon having different physical properties.
What are the physical properties of Carbon and Diamond?Diamond is vary hard whereas graphite is soft;In diamond there is a three dimensional network of strong covalent bonds. This makes diamond extremely hard.
On the other hand, in graphite there are flat layers of carbon atoms. These layers are held by weak van der Waal’s forces and hence can easily slip one over the other. This makes graphite extremely soft and slippery.
Diamond is bad conductor of electricity whereas graphite is a good conductor:In diamond all the four valence electrons carbon are involved in covalent bonds and are not free to conduct electricity. This makes diamond a bad conductor of electricity. In graphite, the fourth valence electron is relatively free, can move from one carbon atom to the other in a layer, and hence is responsible for conducting electricity. Hence, graphite is a good conductor of electricity.
Melting points of graphite and diamond are very high:In diamond as well as in graphite carbon atoms are held by strong net work of covalent bonds. Therefore, both have very high melting points.
Therefore, we can compare the physical properties of carbon and diamond.
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Perform the following
mathematical operation, and
report the answer to the correct
number of significant figures.
]
0.0003/162 = [ ? ]x10
Answer:
1.85 × 10⁻⁶
Explanation:
0.0003 ÷ 162 = 1.851851852 × 10⁻⁶ ⇒ 1.85 × 10⁻⁶
Hope that helps.
The significant figure in the answer should be one here, since the number 0.0003 contains only one significant figure. Hence, the answer is 2 × 10⁻⁶.
What is significant figure ?Significant figures are digits in a quantity with certain values along with some uncertain digits. The counting of significant figures of a number should follow some rules.
The zeros after the decimal point which is not following a nonzero number are not significant. Therefore, there is only one significant figure in the number 0.0003.
For any arithmetic operation, the number of significant figures in the result should be equal to the one in operation that is with least significant figures.
Here. 162 have 3 significant figures. Therefore, the result should contain only one significant figure.
0.0003 /162 = 1.85 × 10⁻⁶.
Then the result with correct significant figures is rounded to 2 × 10⁻⁶.
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differences between plant and animal cells, other than their vacuoles
Answer:
The difference between the two is that plant have three extra "components" than animal. The three extra components include a different sort of vacuole, chloroplast, and a cell wall.
Explanation:
Which part of an investigation is obly found in an experimental investigation?
A. a hypothesis
B. a control group
C. a procedure
D. a conclusion
Answer:
B
Explanation:
The control group is the only answer given that would be found in an experimental investigation. This is because it won't be changed during the experiment. It will remain neutral.
The alpha decay of a radioactive nuclide (X) emits a He-4 nucleus and produces an isotope of Superscript 235 subscript 92 upper U.. What is X?
Answer: Thus X is Plutonium
Explanation:
Alpha Decay: In this process, a heavier nuclei decays into lighter nuclei by releasing alpha particle. The mass number is reduced by 4 units and atomic number is reduced by 2 units.
General representation of alpha decay :
[tex]_{Z}^{A}\textrm{X}\rightarrow _{Z-2}^{A-4}\textrm{Y}+_2^4\textrm{He}[/tex]
where Z = atomic number
A= mass number
X and Y = atomic symbol of elements
[tex]_{Z}^{A}\textrm{X}\rightarrow _{92}^{235}\textrm{U}+_2^4\textrm{He}[/tex]
Thus [tex]_{94}^{239}\textrm{Pu}\rightarrow _{92}^{235}\textrm{U}+_2^4\textrm{He}[/tex]
Thus X is Plutonium with atomic number 94 and mass number 239
Answer:
the answer is D on edge
Explanation:
I NEED HELP PLEASEEE
Answer:
activasion energy
Explanation:
Which example is most likely an inorganic compound?
A. methane, which is made of carbon and hydrogen
B. glucose, which is a sugar made by plants
C. sodium chloride, which is a salt
D. human DNA, which is a molecule in cells
Answer: Easy,the answer is the letter D
Which process is not one of the five general reaction types typically found in biochemistry? group transfers combustions isomerizations oxidation‑reduction reactions
Answer:
Option B (combustion) is the correct approach.
Explanation:
Combustion seems to be a procedure that requires fuel as well as an oxidizing agent response, during which the gaseous oxygen stores energy is set to release. Use a burning has been the oxidation of either fuel.Accelerated oxidizing combustion complemented by heat as well as, commonly, light. A biological confluence accompanied by temperature and light manufacturing process.Some other available scenarios have no connexons with the particular circumstance. So the obvious response to the above was its appropriate one.
LC Chemistry I v18 (GS) / Module 01: Matter
1.(01.05 LC)
Which of the following is an example of a chemical change? (4 points)
Boiling water
Burning paper
Dissolving sugar in water
Melting gold
Answer:
Burning Paper
Explanation:
Burning Paper is an example of a chemical change because;
- A new substance called ''Ash'' is formed.
- It is an irreversible reaction.
In descriptive scientific investigations, scientists often make observations to understand the interacting parts of a complex (blank)
Answer:
Complex System
Explanation:
Given that, a descriptive scientific investigation is one of the three main types of investigation which formulates and quantify the natural phenomenon. This natural phenomenon oftentimes involves Complex System, such as microscopic organisms, thereby, scientists often make observations to understand the interacting parts of this COMPLEX SYSTEM
Hence, the right answer is a COMPLEX SYSTEM
The dimensions of a box are 4.5 cm wide by5.750 cm long by 1.50 cm tall. What is the volume of the box taking significant figures into account?
The volume of the box taking significant figures into account is 38.8125 ≈39 cm³.
What do you mean by volume?
The amount of space occupied by a three-dimensional object or region of space, expressed in cubic units (cm³).
It means, the amount of three dimensional space that a closed figure can occupy is measured by its volume.
Formula for volume=length ×breadth ×height
To calculate the volume of the box,
volume=length × breadth × height
volume=4.5×5.750×1.50
volume=38.8125 ≈39 cm³.
Hence, the volume of the box taking significant figures into account is 38.8125 ≈39 cm³.
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Which describes human-made polymers? synthetic subunit natural macromolecule
Answer:
Synthetic
Explanation:
I just took the quiz and got it right
Answer:
A- Synthetic
Explanation:
just took the quiz
what kind of scientist would study the effects of acid rain on marble statues?
Answer:
A chemist
I hope this helped :D
A sample of seawater weighs 158 g and has a volume of 156 mL. What is the density, in g/
mL, of seawater
1.01 g/ml
Hope this helps :)
A sample of seawater weighs 158 g and has a volume of 156 mL. The density of the seawater is 1.01 g/ml
What is density?Density is the mass per unit volume. Density is denoted by rho and the capital letter D. It can be calculated by dividing the mass by volume.
The volume is the space occupied by a three-dimensional object. It can be calculated by mass and density. It is measured in liters. Mass is the total weight of the object. It is denoted by m.
rho = m / V
rho = density
m = mass
V = volume
The given entities sample of seawater. Its weight is given and the volume is also given.
Given the mass of the sample of seawater weighs 158 mL g.
The volume is 156 ml.
Putting the values in the equation
D = 158 / 156 = 1.01 g/ml
Thus, the density of the seawater is 1.01 g/ml.
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Your mom gives you 6.20 moles of Dr. Pepper. How many particles is that?
Answer:
3.73E-22 particles
1 mole is equal to 6.022E-23 particles (known as avogadro's number). Multiplying 6.20 by 6.022E-23 will cancel out moles and give you particles.
50 POINTS
Match each item with the correct statement below:
1.) The fact that matter can be neither created nor destroyed in a chemical change.
2.) Substance that changes to a gas easily at room temperature.
3.) Any chemical reaction that absorbs energy.
4.) Can be observed only when there is a change in composition of a substance.
5.) Any chemical reaction that gives off energy.
6.) The amount of matter contained in a unit of volume.
7.) The type of change in which the identity of substances does not change.
8.) The change of one or more substances into other substances.
9.) Can be observed without any change in the identity of the substance.
10.) Another term for chemical change.
chemical property
physical change
physical property
chemical change
density
law of conservation of mass
chemical reaction
volatile
endothermic
exothermic
energy
Answer:
1) law of conservation of mass
2) volatile
3) endothermic
4) chemical property
5) exothermic
6) density
7) physical change
8) chemical change
9) physical property
10) chemical reaction
You have 2.2 mol Xe and 2.0 mol F₂, but when you carry out the reaction you end up with only 0.25 mol XeF₄. What is the percent yield of this experiment? Xe(g) + 2 F₂ (g) → XeF₄ (g)
Answer:
The correct answer is 25 %
Explanation:
According to the chemical reaction:
Xe(g) + 2 F₂ (g) → XeF₄ (g)
1 mol of Xe(g) reacts with 2 mol of F₂(g), so the stoichiometric ratio os reactants is 2 mol F₂/mol Xe.
We have 2.2 mol Xe and 2.0 mol F₂, so the ratio is:
2.0 mol F₂/2.2 mol Xe = 0.909 mol F₂/mol Xe
The molar ratio of reactant we have is lower than the required, so F₂ is the limiting reactant.
By using the limiting reactant, we calculate the theoretical amount of product (XeF₄). For this, we know that 1 mol of XeF₄ is formed from 2 mol of F₂ (1 mol XeF₄/ 2 mol F₂), and we have 2.0 mol F₂:
2.0 mol F₂ x (1 mol XeF₄/ 2 mol F₂)= 1 mol XeF₄
If we only obtained 0.25 mol XeF₄, the percent yield of the experiment is:
Yield = experimental amount/theoretical amount x 100%
= 0.25 mol XeF₄/ 1 mol XeF₄ x 100% = 25 %
The percent yield of the solution is 25%.
The equation of the reaction is;
Xe(g) + 2F₂ (g) → XeF₄ (g)
From the reaction equation;
1 mole of Xe reacts with 2 moles of F2
2.2 moles of Xe will react with 2.2 moles × 2 moles /2 moles
= 4.4 moles of F2
We can see that there is not enough F2 hence it is the limiting reactant
2 moles of F2 yields 1 mole of XeF4
2 moles of F2 yields 2 moles × 1 mole/2 moles = 1 mole of XeF4
% yield = actual yield/Theoretical yield × 100
% yield = 0.25 mole/ 1mole × 100
% yield = 25%
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how many w atoms are found in 0.43 moles of pure w
So, neon has a molar mass of 20.18 g/mol , which means that every mole of neon has a mass of 20.18 g . Now, you know that one mole of any element contains exactly 6.022⋅1023 atoms of that element - this is Avogadro's number.
Hope this helped
How does potential energy transform into kinetic energy?
Answer:
When an object is allowed to fall,the concentrated gravitational potential energy is converted into the kinetic energy of motion. if there is no air resistance or other restrictions all of the potential energy will be converted to kinetic energy when the object has fallen the distance H
Explanation
When an object is allowed to fall,the concentrated gravitational potential energy is converted into the kinetic energy of motion. if there is no air resistance or other restrictions all of the potential energy will be converted to kinetic energy when the object has fallen the distance H
Which is one way that scientists communicate the results of an experiment?
Answer:
firstly:scientist communicate with each other to share what they learn
secondly; they question and check each other's work
Answer:
Forming a hypothesis
Explanation:
Cuz why not
describe how 250 cm³ of 0.2 mol/dm³ H2SO4 could be prepared from 150 cm³ of 1.0mol/dm³ stock solution of the acid
Answer:
Explanation:
250 cm^3 of 0.2 moldm-3 H2SO4 can be prepared from 150cm^3 of 1.0 moldm^-3 by dilution.
150cm^3 of the 1.0 moldm^-3 stock solution is measured out using a measuring cylinder and transferred into a 250 cm^3 standard volumetric flask and made up to mark. The resulting solution is now 250cm^3 of 0.2 moldm-3 H2SO4.
Today you will be using the bunsen burner in your experiment. Which of the following is a precaution that should be taken before beginning?
Answer:
See the answer below
Explanation:
Although there are no specific options available to choose from, some of the general safety measures or precautions that must be observed when using a bunsen burner are as follows:
Always leave, at least, 12 inches of space between the bunsen burner and the nearest object. This is to avoid the nearby object catching fire accidentally.Always watch the flame at all times, never leave it unattended to.Burners should not be handled unless ample time has been given for them to cool down. This is to avoid burning-related injuries.Burner fittings should be carefully checked to ensure there are no leakages. Gas leakages may cause serious accidents.Always use a sparker as this is safer than using matches or lighter.The gas supply must always be turned off whenever the burner is not in use.For this experiment, students should wear a lab coat and safety eyewear. Students should not touch the flame. They need to keep loose clothing, jewelry, hair, and any flammable substances away from the flame.
what atom has a greater number of neutrons
Answer:
livermorium
Explanation:
The atom with the largest number of neutrons is a tie between livermorium and tennessine. Each of these atoms contain 177 neutrons.
what is the mass of 0.25 mol of sulfur atom
Answer:
8.0 g
Explanation:
To convert moles to grams, you need to use the molar mass. The molar mass of sulfur is 32.06. The molar mass is the atomic mass of the atom.
(0.25 mol) × (32.06 g/mol) = 8.015 g
Round for significant figures.
8.015 g ≈ 8.0 g
how many significant figures are in 340500
Answer:
there are 4
Explanation:
-20 points-
What chemical would dry ice be in if it were to turn into carbon dioxide?
Answer:
soild from carbon dioxide
All the elements in group 18 are in a gaseous state (state true or false)
Answer:
The correct option is;
True
Explanation:
The noble gases are the group 18 elements, all of which are monoatomic gases, located in the extreme right of the periodic table. Due to their filled outermost or valence shells,and their nonreactive nature, the noble gases where initially known as inert gases.
The noble gases have very low melting points and boiling points as hey have very weak inter atomic forces between their atoms such that they all appear as gases under standard atmospheric temperature and pressure conditions.