Answer:
Because the enthalpy change of the reaction depends on the states of matter of the substances, they must be shown for each substance in the equation.
Explanation:
The enthalpy of a substance depends on the particular state of matter in which it occurs.
Therefore, in a thermo chemical equation, all the states of matters for all the chemical species in the equation must be accurately written so that the thermo chemical equation can be meaningful.
The correct statement about thermochemical equations is the enthalpy
change of the reaction depends on the states of matter of the substances,
they must be shown for each substance in the equation.
Enthalpy is defined as the heat change that occurs in a reaction or the sum
of the internal energy present. It is associated with change in matter and is
dependent on the physical states of the reactants and products.
This is the reason why the physical states such as solid, liquid, gas etc have
to be shown in a thermochemical equation.
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Can a model be improved so much that it leads to truth? Explain your answer.
Answer:
yes it can
Explanation:
a model can be improved so much that it increases your chances of (insert what ever you are writing about) and then describe why:)
A 100-watt light bulb radiates energy at a rate of 100 J/s. (The watt, a unit of power or energy over time, is defined as 1 J/s J/s.) If all of the light emitted has a wavelength of 525nm 525nm, how many photons are emitted per second? Express your answer to three significant figures.
Answer:
Approximately [tex]2.64\times 10^{20}[/tex] (assumption: wavelength [tex]525\; \rm nm[/tex] is measured in vacuum, where the speed of light is approximately [tex]3.0\times 10^{8}\; \rm m \cdot s^{-1}[/tex].)
Explanation:
Convert the unit of wavelength to meters:
[tex]\displaystyle \lambda = 525\; \rm nm = 525 \; \rm nm\times \frac{10^{-9}\; \rm m}{1\; \rm nm} = 5.25 \times 10^{-7}\; \rm m[/tex].
Assume that the wavelength [tex]525\; \rm nm[/tex] is measured in vacuum, where the speed of light is approximately [tex]2.99792\times 10^{8}\; \rm m \cdot s^{-1}[/tex]. Calculate the frequency of this light from its wavelength:
[tex]\displaystyle f = \frac{c}{\lambda} \approx \frac{2.99792\times 10^{8}\; \rm m \cdot s^{-1}}{5.25 \times 10^{-7}\; \rm m} \approx 5.71429\times 10^{14}\; \rm s^{-1}[/tex].
The Planck's Constant can help find the energy of a photon given its frequency. Look up this constant to more than three significant figures:
[tex]h \approx 6.62607\times 10^{-34}\; \rm J \cdot s^{-1}[/tex].
Calculate the energy of one such photon:
[tex]\begin{aligned} E &= h \cdot f\\ &\approx 6.62607\times 10^{-34}\; \rm J \cdot s^{-1} \times 5.71023\times 10^{14}\; \rm s \\ &\approx 3.78370\times 10^{-19}\; \rm J \end{aligned}[/tex].
Calculate the number of these photons that [tex]100\; \rm J[/tex] of energy can produce under the assumption of [tex]100\%[/tex] conversion:
[tex]\displaystyle \frac{100\; \rm J}{3.78370\times 10^{-19}\; \rm J} \approx 2.64\times 10^{20}[/tex].
(Rounded to three significant figures.)
The mole is derived from the quantity of atoms in 12 grams of carbon-12. The mole is just a number, it can be used for:_________
Answer:
Explanation:
A mole is the amount of substance that contains as many elementary entities as there are carbon atoms in 12 grams of carbon -12 isotopes i.e. it is the amount of a substance that posses the same number of particles as the number of atoms in exactly 12g of carbon is 12.
The number of atoms in a mole is known to be the Avogadro Number which is equal to 6.02 × 10²³. Thus, a mole of any substance is that amount of the substance which contains 6.02 × 10²³ particles of that substance. The definition of the mole is also given by the relationship:
[tex]\mathtt {moles = \dfrac{ mass \ in \ grams}{ relative \ molecular \ mass}}[/tex]
Desceibe each of the following as a measured number or an exact number:5 books5 Ib9.23 g0.035 kg12 roses12 inches in 1 foot361 miles100 cm in 1 mHow do you determine the last digit in any measured number?
Answer:
The last digit in any measured quantity of a tool is the minimum it can measure so
5 books ---- Exact number
5 lb ---- measured
9.23 g----- measured
9.035Kg measured
12 roses ------ exact
12 inches in 1 foot ----- exact
361 miles ------- measured
100 cm in 1 m ------- exact
Eric's father asked an engineer to survey the field behind their house. He wanted to plant some apple and pear trees there. According to the survey, the field is 38 meters (m) long and 17 meters (m) wide. What is the perimeter of the field in centimeters?
Answer:
11,000 cm
Explanation:
Step 1: Given data
Width of the field (w): 17 meters
Length of the field (l): 38 meters
Step 2: Calculate the perimeter of the field
The field is a rectangle. We can find its perimeter (P) by adding its sides.
P = 2 × w + 2 × l = 2 × 17 m + 2 × 38 m = 110 m
Step 3: Convert the perimeter to centimeters
We will use the relationship 1 m = 100 cm.
110 m × (100 cm/1 m) = 11,000 cm
how many pi bonds do triple bonds have
Answer:
Two pi bonds, one sigma bond.
Explanation:
A triple bond has three bonds:
2 pi bonds, and one sigma bond.
Answer:
Two pi bonds & one sigma bond.
A triple bond is made of:
2 pi bonds1 sigma bondHope it helps!
From his experiments, J. J. Thomson concluded that cathode ray particles can move at very fast speeds. cathode ray particles can be moved by electric current. atoms contain small positively charged particles that are called protons. atoms contain small negatively charged particles that are called electrons. Mark this and return
Answer:atoms contain small negatively charged particles that are called electrons
Explanation:
In an electrically neutral atom,
o the number of protons equals the number of
neutrons.
the number of protons equals the number of
electrons.
the number of neutrons equals the number of
electrons.
Answer:
the number of Protons equals the number of Electrons.
Explanation:
Edg 2021
In an electrically neutral atom, the number of protons equals the number of electrons. Thus, the correct option for this question is B.
What are Protons?Protons may be defined as the type of sub-atomic particles that are present in the nucleus of an atom along with neutrons. These sub-atomic particles are positively charged in nature. Protons are thought to be discovered by Ernest Rutherford.
Electrons are also the type of sub-atomic particles which are continuously revolving around the nucleus of an atom. These sub-atomic particles are negatively charged in nature.
So, when the number of protons is more as compared to the number of electrons, an atom possesses a positive charge while the number of protons is found to be less compared to the number of electrons, and an atom possesses a negative charge.
Therefore, in an electrically neutral atom, the number of protons equals the number of electrons. Thus, the correct option for this question is B.
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A saline solution contains 0.800 g of NaCl (molar mass 58.55 g/mol) in 54.6 mL of solution. Calculate the concentration of NaCl in this solution, in units of molarity Express the concentration in molarity to three significant figures.
Answer:
0.25 M
Explanation:
Data obtained from the question include:
Molar mass of NaCl = 58.55 g/mol
Mass of NaCl = 0.800 g
Volume = 54.6 mL
Next, we shall determine the number of mole in 0.800 g of NaCl. This can be obtained as follow:
Molar mass of NaCl = 58.55 g/mol
Mass of NaCl = 0.800 g
Mole of NaCl =?
Mole = mass /Molar mass
Mole of NaCl = 0.8/58.55
Mole of NaCl = 0.0137 mole
Next, we shall convert 54.6 mL to litres (L). This can be obtained as follow:
1000 mL = 1 L
Therefore,
54.6 mL = 54.6 /1000
54.6 mL = 0.0546 L
Finally, we shall determine the molarity of the solution as follow:
Mole of NaCl = 0.0137 mole
Volume = 0.0546 L
Molarity =?
Mol= mole /Volume
Molarity = 0.0137/0.0546
Molarity = 0.25M
Therefore, the molarity of the solution is 0.25 M
5 pois
Energy pyramids illustrate the transfer of 10% of the energy stored by
producers flowing from the bottom level to primary consumers. What
happens to the other 90% of the energy?
О
The remaining 90% is transformed for life activities such as movement, growth, or
released as heat.
The remaining 90% evaporates into the atmosphere.
The remaining 90% transforms into Hydrogen and Oxygen.
The remaining 90% is recombined to maker larger molecules.
Explain why heat is often used in a laboratory experiment. a. To warm up the laboratory, b. To speed up a reaction
Answer:
To speed up a reaction
Explanation:
Heat, as well as catalysts, increase the reaction rate of some chemical reactions since they cause the enzymes or reagents in charge of carrying out the transformation to products to act faster and increase their kinetic energy of reaction.
what is the formula for tetrasulfur hexabromide
If you answer I will give you a brainliest
Answer:
Tetrasulfur Dinitride S4N2
Tetrasulfur pentoxide S4N4
Tetrasulfur tetranitride N4S4
Tetrasulfur pentoxide S4N4
A sample of motor oil has a mass of 440 g and a volume of 0.27 L. What is its
density (in g/mL)?
Answer:
Density =1.63 g/mLExplanation:
The density of a substance can be found by using the formula
[tex]Density = \frac{mass}{volume} [/tex]
To find the density in g/mL , we must first convert the volume from L to mL
From the question
mass = 440 g
1 L = 1000 mL
0.27 L = 0.27 × 1000 = 270 mL
volume = 270 mL
Substitute the values into the above formula and solve for the Density
That's
[tex]Density = \frac{440}{270} [/tex]
= 1.629629...
We have the final answer as
Density =1.63 g/mLHope this helps you
Whose work directly resulted in the development of an atomic model that has negative electrons stuck within a sea of positive material? Democritus Rutherford Thomson Dalton
Answer:
Thomson
Explanation:
Atomic models were proposed after the discovery of the atom and the sub-atomic particles. Thomson's model of the atom portrayed electrons stuck in the sea of protons. Thus, option C is correct.
What is Thomson's atomic model?J. J. Thomson proposed the model for atoms and their sub-atomic particles called electrons and protons. It was an important model that depicted the presence of the sub-atomic particles in the atom.
According to him, the electron had been known to carry a negative charge that was stuck in the soup or the sea of the positively charged protons. It resembled a plum cake that has electrons stuck in them as the cherries or the plum.
Therefore, the atomic model of the electron stuck in the sea of protons was given by J. J. Thomson.
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Buck's Turf Care Company mowed 229 lawns over a 18 week period. What is the average weekly rate of mowing lawns?
Answer:
Average weekly rate of mowing lawns = 13 lawns (Approx)
Explanation:
Given:
Total lawns mowed = 229
Total number of period = 18 week
Find:
Average weekly rate of mowing lawns
Computation:
Average weekly rate of mowing lawns = Total lawns mowed / Total number of period
Average weekly rate of mowing lawns = 229 / 18
Average weekly rate of mowing lawns = 12.72
Average weekly rate of mowing lawns = 13 lawns (Approx)
A car traveling north with a velocity of 30 m/sec slows down to a velocity of 10 m/sec
within 10 sec. What is the car's acceleration?
Answer:
-2m/s/s
Explanation:
Acceleration = change in speed / change in time
Change in speed = final speed - initial speed
In this case the change in speed was 10m/s - 30m/s = -20m/s
And change in time was 10 sec (within 10 sec)
Therefore acceleration = -20/10 = -2m/s/s
The acceleration is negative because the car slowed down (decelerated essentially) and the unit for acceleration is meters per second per second because it is the change in speed per second.
Hope this helped!
Challenge: In a 60 km/h speed zone the police set up a digitector, placing 2 cables across the road, 5m apart The time taken for cars to cross both cables was recorded. One car took 0.2 seconds to cross the cables. Was it speeding? If so by how much?
Answer:
The answer to your question is given below.
Explanation:
The following data were obtained from the question:
Speed limit = 60 km/h
To know if the car was speeding, let us calculate the speed of the car.
This can be obtained as follow:
Distance (d) = 5 m
Convert 5 m to km
Recall:
1000 m = 1 km
5 m = 5/1000
5 m = 0.005 km
Time (t) = 0.2 sec.
Convert 0.2 sec to hour.
Recall:
3600 secs = 1 h
Therefore,
0.2 sec = 0.2/3600
0.2 sec = 5.56×10¯⁵ h
Thus,
Distance (d) = 0.005 km
Time (t) = 5.56×10¯⁵ h
Speed of car =?
Speed = Distance /time
Speed = 0.005/5.56×10¯⁵
Speed of the car = 90 km/h
Comparing the speed of the car (i.e 90 km/h) to the speed limit of the zone (i.e 60 km/h), we can see that the car is on a high speed since its speed (i.e 90 km/h) is higher than the speed limit of the zone (i.e 60 km/h).
Speed of the car = 90 km/h
Speed limit = 60 km/h
Difference = 90 – 60
Difference = 30 km/h
Therefore, the car is speeding by 30 km/h more compared to the speed limit.
Rank the following compounds from most acidic to least. To rank items as equivalent, overlap.A. CH3NH2B. CH3OH+C. 2CH3OH
Is this basalt homogeneous or heterogeneous?
Answer:
heterogeneous
Explanation:
A mountaineer shouts for help Half a second later (0.5 she hears the echo How far away is the rock face which is reflecting her voice (take the speed of sound to be 330 m\s) help please I will mark brain liest
Answer:
THE DISTANCE OF THE ROCK REFLECTING HER VOICE IS 82.5 METERS.
Explanation:
In sound waves, the speed of a sound is equal to twice the distance divided by time.
Mathematically,
Speed = 2 * Distance/ Time
Speed = 33- m/s
Time = 0.5 second
Distance = unknown
So re-arranging and introducing the variables into the formula, we have;
Distance = speed * time / 2
Distance = 330 * 0.5 / 2
Distance = 82.5 meters.
The distance away from the rock face which is reflecting her voice is 82.5 meters.
find how many natural numbers are there between 80 and 120 step by step plz
The concentration of Salt Solution is teams
of mass by mass it is 20% and the
mass of the Solution IS 550
Detrmine the mass of Solute Present
in th Solution?
Answer:
11
Explanation:
so that is 20\100× 55 that gives you 11
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You are given a mixture consisting of marbles, iron filings, sugar and sand. Suggest a series of steps for separating this mixture. You may make a flowchart, but be careful to fully explain each step (Why are you using that method?). When you are finished, you should have each component of the mixture in a separate beaker.
Answer:
Explanation:
Start by sifting the marbles out bc they are bigger they will sit in a big sifter
Than with a magnet roll it in what’s left this will pick up all the iron pieces
Than Fill with water and stir this should resolve the sugar which after you sift out the sand you can heat and scrape off beaker and than for a very short time heat up the sand to dry it and not have extra weight from the water
!!!sand only for a few seconds or else it will fly everywhere and if it gets in eye it will sting badly
Date
Pages
Equivalent weight of the compound
caco3
Answer:
CaCO3,which is Calcium Carbonate. It’s equivalent mass is 50 g. Explanation:-. Mass of CaCO3=Mass of 1 atom of Calcium (Ca)+Mass of 1 atom of Carbon (C)+Mass of 3 atoms of Oxygen (O). Mass of 1 atom of Calcium=1×40g=40g. Mass of 1 atom of Carbon=1×12g=12g. Mass of 3 atoms of Oxygen=3×16g=48g.
Explanation: Hope this helps :)
what is connecting wire in science
Answer:
Connecting wires provide a medium to an electrical current so that they can travel from one point on a circuit to another. ... In a basic circuit, the wire comes from one terminal of a power source, then connects to a switch that determines whether the circuit is open or closed.
Explanation:
How many moles and numbers of ions of each type are present in the following aqueous solutions?
(a) 88 mL of 1.75 M magnesium chloride,
(b) 321 mL of a solution containing 0.22 g aluminum sulfate/L,
(c) 1.65 L of a solution containing 8.83×10218.83×1021 formula units of cesium nitrate per liter.
Answer:
a. 0.154 moles = 2.78x10²³ ions
b. 2.18x10⁻⁴ moles = 6.56x10²⁰ ions
c. 1.77x10²² ions = 0.0147 moles
Explanation:
The multiplication of volume of solution in liters times molarity gives the moles of solute.
a. Moles MgCl₂:
88mL = 0.088L * (1.75mol / L) = 0.154 moles MgCl₂
Uaing Avogadro's number:
0.154mol *(6.022x10²³ molecules / 1 mol) = 9.27x10²² molecules.
As 1 molecule of MgCl₂ contains 3 ions:
Ions = 2.78x10²³
b. Moles Al₂(SO₄)₃:
Aluminium sulfate has a molar mass of 324.15g/mol:
0.321L * (0.22g Al₂(SO₄)₃ / L) * (1mol / 324.15g) = 2.18x10⁻⁴ moles.
1 molecule contains 5 ions:
2.18x10⁻⁴ moles *(6.022x10²³ molecules / 1 mol) * 5 = 6.56x10²⁰ ions.
c. 8.83x10²¹ formula units of CsNO₃ = Number of molecules. Ions are:
8.83x10²¹ * 2 = 1.77x10²² ions
And moles are:
8.83x10²¹ Formula units * (1mol / 6.022x10²³) = 0.0147 moles
a. The number of moles and number of ions should be 0.154 moles and 2.78x10²³ ions
b. The number of moles and number of ions should be 2.18x10⁻⁴ moles and 6.56x10²⁰ ions
c. The number of moles and number of ions should be 1.77x10²² ions and 0.0147 moles
Calculation of the no of moles and no of ions:a. Moles MgCl₂:
Here,
88mL = 0.088L * (1.75mol / L) = 0.154 moles MgCl₂
Now here we used Avogadro's number:
So,
0.154mol *(6.022x10²³ molecules / 1 mol) = 9.27x10²² molecules.
Since 1 molecule of MgCl₂ contains 3 ions:
So,
Ions = 2.78x10²³
b. Moles Al₂(SO₄)₃:
Since Aluminum sulfate has a molar mass of 324.15g/mol:
So,
0.321L * (0.22g Al₂(SO₄)₃ / L) * (1mol / 324.15g) = 2.18x10⁻⁴ moles.
Now
1 molecule contains 5 ions:
So,
2.18x10⁻⁴ moles *(6.022x10²³ molecules / 1 mol) * 5 = 6.56x10²⁰ ions.
c. Since
8.83x10²¹ formula units of CsNO₃ = Number of molecules. Ions are:
So,
8.83x10²¹ * 2 = 1.77x10²² ions
And moles are:
8.83x10²¹ Formula units * (1mol / 6.022x10²³) = 0.0147 moles
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Convert 1,650,000 centimeters to kilometers.
0 1.65 kilometers
16.5 kilometers
0 165 kilometers
1,650 kilometers
Answer:
16.5 kilometers is your answer
Answer:
16.5
Explanation:
Lead has a density of 11.34 g/mL, if you weigh an empty beaker and it weighs 245.61 grams, then add lead until the scale reads 350.52 grams, what is the volume of lead that you have? *
Answer:
Explanation:
wt. of the lead = wt. of ( flask + lead) - wt.of the empty flask
350.52- 245.61= 104.91 grams of lead
density = mass/volume
11.43= 104.91/V
V = 9.178 ml
What should scientists do after completing a scientific investigation?
o write a hypothesis
confirm the results
O design the procedure
make observations
D. Make observations
The first thing you do is write a hypothesis then you were designed your procedure, after you make the procedure you would do the procedure, after you do the procedure you would confirm the results, then at the end you would make observations to see that everything is correct.
Which of the following compounds are ionic?
a. KCl
b. C2H4
c. BaCl2
d. SiCl4
e. LiF
Answer:
a. KCl, c. BaCl2 and e. LiF.
Explanation:
Hello,
In this case, we can identify the ionic compounds by verifying the difference in the electronegativity between the bonding compounds when it is 1.7 or more (otherwise it is covalent) as shown below:
a. KCl: 3.0-0.9=2.1 -> Ionic.
b. C2H4: 2.5-2.1=0.4 -> Covalent.
c. BaCl2: 3.0-0.8=2.2 -> Ionic.
d. SiCl4: 3.0-1.8=1.2 -> Covalent.
e. LiF: 4.0-1.0=3.0 -> Ionic.
Therefore, ionic compounds are a. KCl, c. BaCl2 and e. LiF.
Regards.