Answer:
Explanation:
You will need to look up the Standard Heats of Formation* for each substance and apply Hess's Law Equation.
ΔH⁰(rxn) = ∑ΔH⁰(Products) - ∑ΔH⁰(Reactants)
*Std Heats of Formation can be found in the appendix of most college chem texts.
For this problem:
Given CaCO₃(s) => CaO(s) + CO₂(g)
∑ΔH⁰: -635.1 Kj/mole -393.5Kj/mole -1206.9
ΔH⁰(rxn) = [(-393.5 Kj/mole) + (-393.5Kj/mole)] - (-1206.9Kj/mole)
= (-635.1 -393.5 + 1206.9) Kj/mole
= +178.3 Kj/mole
Answer:
656.3 kJ
This reaction is endothermic
Explanation:
edge 2020
HELP I'LL AWARD BRAINLIEST
Answer:
slope of line a: y=2x-2
slope of line b: y=2x+2
slope of line c: y=1x+2
Explanation:
hope this helps!!
Plzzzzz help me answer this question (WILL AWARD BRAINLIEST)
Which of these does not accurately describe the Wright brothers' first
airplane?
A. It had wings that flapped,similar to birds wings
B.it had powerful yet exceptionally lightweight engines
C.it was created after various designs were tested in a wind tunnel
D.it was created using the engineering process
Answer: A
Explanation:
it had wings that flapped, similar to birds' wings.
Which answer below correctly identifies the type of change and the explination for the boiling of water
What is a hypothesis? O a part of the scientific method that is not necessary a specific and testable question O the variables I observe during the experiment HELP HELP PLS PLS PLS HELP NoW NowWWwWw I'll mark u BRAINLIEST!!!!!!!!
Define molecular mass. Calculate the molecular mass of calcium carbonate
and nitric acid.
Answer:
HNO₃ =63.0147 g/mol
CaCO₃ = 100.088 g/mol
Explanation:
Molecular mass:
It is the sum of all the atomic masses of the atoms of elements present in a molecule.
For example:
The formula of CaCO₃:
Calcium carbonate consist of one atom of calcium, one atom of carbon and three atoms of oxygen. Thus, its molecular mass would be,
CaCO₃ = 40.078 × 1 + 12.01×1 + 16.00×3
CaCO₃ = 40.078 + 12.01+ 48
CaCO₃ = 100.088 g/mol
The formula of HNO₃:
Nitric acid consist of one atom of hydrogen, one atom of nitrogen and three atoms of oxygen. Thus, its molecular mass would be,
HNO₃ =1.008 × 1 + 14.0067 ×1 + 16.00×3
HNO₃ = 1.008 +14.0067 + 48
HNO₃ =63.0147 g/mol
What is the density (g / mL) of a substance that has a mass of 8.11 g and, when placed into a graduated cylinder, causes the water level to rise from 25.26 mL to 44.72 mL?
Answer:
The answer is 0.42 g/mLExplanation:
The density of a substance can be found by using the formula
[tex]density = \frac{mass}{volume} \\[/tex]
From the question
mass = 8.11 g
volume = final volume of water - initial volume of water
volume = 44.72 - 25.26 = 19.46 mL
We have
[tex]density = \frac{8.11}{19.46} \\ = 0.416752312...[/tex]
We have the final answer as
0.42 g/mLHope this helps you
Which pair has the stronger ionic bond:
- MgCl2 vs. NaCl2
- NaCl vs. LiCl
Which molecule would have this shape?
Answer:
CO2
Explanation:
the subscript tells you how many of one element is used for this case there is one black atom and 2 red ones so you only need 1 carbon and 2 oxygens.
hope this helps. brainliest please?
3.7500*10^4+9.7100*5
Answer:
37548.55
Explanation:
3.7500*10^4+9.7100*5
3.7500*10000+9.7100*5
37500+48.55
37548.55
Which evidence did Alfred Wegener use as evidence for the Continental Drift Theory?
Group of answer choices
A)South America and Africa fit like a puzzle.
B)Matching fossils on different continents
C)Similar rock types on the East coast of North America and Western Europe
D)All of the above
12 PTS!! WILL GIVE BRAINLIEST!! DUE TODAY!!
The experiment is increasing and decreasing the amount of predators, pollution, and food to see how the cricket frogs will react.
Test variable (independent variable):
Outcome variable (dependent variable):
Control group:
Answer:
Test variable (independent variable): Predators, Pollution, Food.Outcome variable (dependent variable): Cricket Frogs.Control group: Beginning Frog Count
Explanation:
If pollution isincreased, then the cricket frog population will (stay the same) over the span offive years.If the amount of food available isincreased, then the cricket frog population will (increase) overthe span of five years.Procedure:The procedures are listed in your virtual lab. You do not need to repeat them here. Please be sureto identify the test variable (independent variable), outcome variable (dependent variable), andcontrol group for this experiment.
If I have 21,000 mL of gas at a temperature of 870C and a pressure of 101 atm, what will be the pressure of the gas if I raise the temperature to 1040C and decrease the volume to 15 liters?
Answer:
We have,
Initial volume is V
1
Initial temprature is T
1
=75
0
C
Initial pressure is P
1
So, final temprature is T
2
=273+75=348K
V
2
=V
1
−
100
15
V
1
=
100
85V
1
Applying the gas formula,
T
1
P
1
V
1
=
T
2
P
2
V
2
348
P
1
V
1
=
T
2
×100
2P
1
×85V
1
T
2
=
100
2×85×348
T
2
=591.6K
Question 4
Volume is what type of physical property?
Write the complete ionic equation for the reaction that takes place when aqueous solutions of strontium hydroxide and lithium phosphate are mixed.
Answer : The net ionic equation will be,
[tex]3Sr^{2+}(aq)+2PO_4^{3-}(aq)\rightarrow Sr_3(PO_4)_2(s)[/tex]
Explanation :
In the net ionic equations, we are not include the spectator ions in the equations.
Spectator ions : The ions present on reactant and product side which do not participate in a reactions. The same ions present on both the sides.
The given balanced ionic equation will be,
[tex]3Sr(OH)_2(aq)+2Li_3PO_4(aq)\rightarrow 6LiOH(aq)+Sr_3(PO_4)_2(s)[/tex]
The ionic equation in separated aqueous solution will be,
[tex]3Sr^{2+}(aq)+6OH^{-}(aq)+6Li^{+}(aq)+2PO_4^{3-}(aq)\rightarrow Sr_3(PO_4)_2(s)+6Li^+(aq)+6OH^{-}(aq)[/tex]
In this equation, [tex]Li^+\text{ and }OH^-[/tex] are the spectator ions.
By removing the spectator ions from the balanced ionic equation, we get the net ionic equation.
The net ionic equation will be,
[tex]3Sr^{2+}(aq)+2PO_4^{3-}(aq)\rightarrow Sr_3(PO_4)_2(s)[/tex]
The complete ionic equation for the reaction between aqueous solutions of strontium hydroxide and lithium phosphate is:
3Sr²⁺(aq) + 6OH¯(aq) + 6Li⁺(aq) + 2PO₄³¯(aq) —> Sr₃(PO₄)₂(s) + 6Li⁺(aq) + 6OH¯(aq)
The complete ionic equation is simply an equation showing all available entities including the spectator ions present in the solution.
With the above information in mind, we shall write the complete ionic equation for reaction between aqueous solutions of strontium hydroxide and lithium phosphate. This can be obtained as follow:
In solution, strontium hydroxide, Sr(OH)₂ and lithium phosphate, Li₃PO₄ will dissociate as follow:
Sr(OH)₂(aq) —> Sr²⁺(aq) + 2OH¯(aq)
Li₃PO₄(aq) —> 3Li⁺(aq) + PO₄³¯(aq)
The reaction will proceed as follow:
Sr(OH)₂(aq) + Li₃PO₄(aq) —>
Sr²⁺(aq) + 2OH¯(aq) + 3Li⁺(aq) + PO₄³¯(aq) —> Sr₃(PO₄)₂(s) + 3Li⁺(aq) + 2OH¯(aq)
Balance the equation by writing 3 before Sr²⁺, 6 before OH¯, 6 before Li⁺ and 2 before PO₄³¯, to obtain the complete ionic equation as shown:
3Sr²⁺(aq) + 6OH¯(aq) + 6Li⁺(aq) + 2PO₄³¯(aq) —> Sr₃(PO₄)₂(s) + 6Li⁺(aq) + 6OH¯(aq)
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Which is the most effective action for people to take in order to reduce greenhouse gas emissions? O taking the bus more often O using a car powered by fuel cells O driving a car only five days a week O using a car that travels farther on each gallon of gas
One of the most effective ways to reduce greenhouse gases is using a car powered by fuel cells.
What are greenhouse gases?The term greenhouse gases refers to those gases that lead to a rise in the temperature of the earth due to the re-radiation of infrared rays towards the surface of the earth.
It is very important to take vital steps in order to prevent the emission of these gases. One of the most effective ways to reduce greenhouse gases is using a car powered by fuel cells.
Learn more about greenhouse gases: https://brainly.com/question/14131369?
Answer:
Using a car powered by fuel cells
Explanation:
B On Edge
Other than lowering the cost of producing coins, what could be another added benefit of changing the metals used to make coins?(hint: think of the density...why would a metal that is less dense be beneficial?)
Answer:
See explanation
Explanation:
A coin is money made from metal stuff. Common coinage metals are copper, silver, nickel etc.
One consideration in coin production is the density of the coin. A coin of less density will have lesser mass and occupy a lesser volume. This makes it easier to carry the coin around.
Coins should therefore be made of low density metals so that they can easily be carried about.
A given volume of gas at a temperature of 100 K has a
pressure of 225 kPa. At a higher temperature, the same
volume of gas has a pressure of 450 kPa. At what
temperature does the gas have this higher pressure?
Answer:
200K
Explanation:
Pressure is directly proportional to temperature.
100=225
x=450
(100*450)/225=x
x=45000/225
x=200
What is the weight of 12.0 moles of water?
Answer:
216g H2O
Explanation:
H = 1
O = 16
H= 2 × 1 = 2
O= 1 × 16 = 16
16 + 2= 18g/mol
18g H2O = 1 mol
X g H2O = 12 mol
X × 1 = 18 × 12
X = 216 g/mol
The weight of 12.0 moles of water is determined as 216 g.
What is the weight of the water?The weight of water is determined from the molecular weight of water. The molecular weight of water is given 18 g/mol.
The weight of 12 moles of water is calculated as follows;.
W = nM
W = 12mole x 18 g/mol
W = 216 g
Thus, the weight of 12.0 moles of water is determined as 216 g.
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When a solid is placed in a container and heat is applied, a phase change occurs. Watch the video and identify which of the following statements are correct.
a) The temperature increases while all of a liquid is converted to a gas.
b) The average kinetic energy of the system changes while all of a solid is converted to a liquid.
c) Temperature remains constant while all of a solid is converted to a liquid.
d) When heat is applied to a solid, the molecular motion decreases as the temperature increases.
e) When a solid is converted to a liquid, heat is absorbed.
Answer:
Temperature remains constant while all of a solid is converted to a liquid.
When a solid is converted to a liquid, heat is absorbed.
Explanation:
During a phase change, the temperature of the system remains constant. Recall that latent heat is defined as heat that causes a change of state without a corresponding rise in temperature of the system.
When a solid is converted to a liquid, latent heat of fusion is involved hence the temperature of the system remains constant throughout the process.
Similarly, heat is absorbed as intermolecular forces are broken up and the would converts to liquid.
what does it mean for electrons to be excited
Answer:
When an electron temporarily occupies an energy state greater than its ground state, it is in an excited state. An electron can become excited if it is given extra energy, such as if it absorbs a photon, or packet of light, or collides with a nearby atom or particle.
Explanation:
Hope this helps.
Have a good night ma´am/sir.
Be safe!
How many moles are in 1.93x1023 particles of Na3PO4?
Answer:
The answer is 0.32 molesExplanation:
To find the number of moles given the number of entities we use the formula
[tex]n = \frac{N}{L} \\ [/tex]
where n is the number of moles
N is the number of entities
L is the Avogadro's constant which is
6.02 × 10²³ entities
From the question
N = 1.93 × 10²³ particles
We have
[tex]n = \frac{1.93 \times {10}^{23} }{6.02 \times {10}^{23 } } \\ = 0.320598006...[/tex]
We have the final answer as
0.32 molesHope this helps you
No. of particles of Na₃PO₄ = 1.93×10²³
We have to find number of moles of the given compound[tex].[/tex]
Number of moles cam be found by using this formula :
[tex]\bigstar\:\boxed{\bf{\purple{n=\dfrac{N}{N_A}}}}[/tex]
n denotes number of molesN denotes number of particles[tex]\sf{N_A}[/tex]denotes avogadro's constantWe know that,
[tex]\bf{N_A}[/tex] = 6.022×10²³★ Calculation :
➠ n = N/[tex]\sf{N_A}[/tex]
➠ n = (1.93×10²³)/(6.022×10²³)
➠ n = 0.32 moles
★ Explore More :
n = weight / Molar massn = volume / 22.4Hope It Helps!pleaseeeeeeeeeeee help me
Answer:
4740460000, or 4.74046*10^9
Explanation:
This is math i thnk
e means *10
[tex]5.63\cdot \:8.42\cdot \:10^{19-11}[/tex]
[tex]5.63\cdot \:8.42\cdot \:10^8[/tex]
[tex]10^8\cdot \:47.4046[/tex]'
<3
Red
ok so this is saying
5.63 x 10^19 * 8.42 x 10^-11 indicates a scientific notation
plug into your graphing calculator and you get 4740460000 but make it imto three sig figs so the answer is: 4.74 x 10^9
Which one of the following reactions would produce the largest amount of heat
per mole of hydrogen?
A) C(s) + 2 H2 (g) CH4 (g) AH° = -74.9
kJ/mol
B) N2O (g) + 3 H2 (g) N2H4 (g)+ H2O (l)
AH° = -316.8 kJ/mol
C) 2 H2(g) + O2 (g) 2 H2O (l) AH° = -571.6
kJ/mol
D) N2 (g) + 3 H2 (g) 2 NH3 (g) AH° = -91.8
kJ/mol
Answer:
C) 2 H2(g) + O2 (g) 2 H2O (l) AH° = -571.6
kJ/mol
Explanation:
The magnitude of heat released in an exothermic reaction is shown by the magnitude of the change in enthalpy.
The more negative the enthalpy change of the reaction, the more the heat released by the process.
Hence, 2 H2(g) + O2 (g) 2 H2O (l) AH° = -571.6 kJ/mol has the most negative value of enthalpy change hence the greatest amount of heat is released in this reaction.
The reaction which would produce the largest amount of heat per mole of hydrogen is; Choice C: 2H2(g) + O2 (g). ===> 2 H2O (l) AH° = -571.6
AH° = -571.6kJ/mol.
According to the question;
We are required to identify the reaction which would produce the largest amount of heat per mole of hydrogen.It is evident that all the reactions are exothermic; the reactions release heat.
In essence, the reaction which produces the largest amount of heat is that with the largest negative enthalpy change, AH.In this scenario; the reaction that would produce the largest amount of heat per mole of hydrogen is Choice C: 2H2(g) + O2 (g) =====> 2 H2O (l) AH° = -571.6 kJ/mol
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How many elements are in a isotope?
Answer:i believe 9-?
Explanation:
boron-10
boron-11
carbon-12
carbon-13
oxygen-16
oxygen-17
oxygen-18
chlorine-35
chlorine-37
*
2. Which of the following is an example of mass?
O A. 7 cm3 of air in a balloon
B. 1 mL of water in a test tube
O C. 4 centimeter piece of string
D. 8 kilograms of bananas
How many types of rocks can form from the rock cycle?
0 1
02
O 3
04
Answer:
Sedimentary, igneous and metamorphic
Metomorphic, heat and pressure
Sedimentary erosion and weather
Igneous magma and lave
So three!
What do any two samples of the element mercury (Hg) have in common?
A.the same mass
B.the same volume
C.the same type of atoms
D.the same number of electrons
Answer:
C
Explanation:
The same types of atoms
To see the number of atoms of an element in a given molecule we need to multiply stoichiometry to the number that is written on the foot of the element that is stoichiometry. The correct option is option C.
What is atom?Atom is the smallest particle of any element, molecule or compound. Atom can not be further divided. Atoms contains nucleus in its center and electron that revolve around the atom in fixed orbit.
In the nucleus of an atom, proton and neutron are present. Electron has -1 charge while proton has +1 charge. Neutron is neutral that is it has no charge. So overall the charge of nucleus is due to only proton, not by neutron. The two samples of the element mercury (Hg) will have same type of atoms.
Therefore, the correct option is option C.
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What are the steps to
separate iron fillings, water,
leaves?
Answer:
Wrap a magnet in plastic lunch wrap and move it through the mixture of the three solids. The iron filings will stick to the magnet. The filings can be removed by unwrapping the plastic from the magnet carefully! Mix the remaining salt and sand in water and stir.
Explanation:
Round the value 44.981 g to three significant figures.
Answer:
45.0
Explanation:
Using the rules of rounding, we can round 44.981 to 45. We need that third sig fig though, so we add the trailing zero
The value 44.981 g to three significant figures is 45.0 g.
Significant figures, also known as significant digits, are the digits in a number that carries meaning in terms of precision and accuracy. They indicate the certainty or reliability of a measurement or calculated value.
To round the value 44.981 g to three significant figures, follow the rules for significant figures:
Identify the three most significant digits in the number. They are 4, 4, and 9.
Look at the digit immediately after the third significant digit. If it is 5 or greater, round up; if it is less than 5, round down.
In 44.981 g, the digit immediately after the third significant digit (9) is 8. Since 8 is greater than 5, round up.
Therefore, rounding 44.981 g to three significant figures gives us:
45.0 g.
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