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).
Radon-220 undergoes alpha decay with a half-life of 55.6 s.?
Assume there are 16,000 atoms present initially and calculate how many atoms will be present at 0 s, 55.6 s, 111.2 s, 166.8 s, 222.4 s, and 278.0 s (all multiples of the half-life). Express your answers as integers separated by commas.
Calculate how many atoms are present at 50 s, 100 s, and 200 s (not multiples of the half-life).
The half life of a radioactive isotope refers to the time taken for half of the number of original number of atoms present in the sample to decay.
The equation below gives the number of atoms present at time t
[tex]N=Noe^-kt[/tex]
N = Number of atoms present at time t
No = Number of atoms initially present
k = decay constant
t = time taken
Given that;
t1/2 = 0.693/k
where t1/2 = half life
k = 0.693/t1/2
k = 0.693/ 55.6 s
k = 0.0125 s-1
Substituting values;
N = 16,000 e^-0.0125(0)
N = 16,000 atoms
At 50 s
N = 16,000 e^-0.0125(50)
= 8564 atoms
At 100 s
N = 16,000 e^-0.0125(100)
= 4584 atoms
At 200 s
N = 16,000 e^-0.0125(200)
= 1313 atoms
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choose isomer of hexanoic acid?
A) - penthylformiate
B) _ izopropyleacetate
C) _ methylpropanoate
D) _ a- Methylbutanoic acid
Answer:
THR ANSWER IS C) _ methylpropanoate
Which is a statement of cell theory? All cells are made up of living molecules. All plants are made of cells. All animals are made of cells. All cells are produced from other cells.
Answer:
all cells are produced from other preexisting cells through cell division
8. Build a neutral lithium atom.
Now, what must you do to make the lithium atom's charge change to +1?
Hint: Lithium is atomic number 3.
Add 2 electrons
Remove 1 electron
Add 1 electron
Add 1 proton
Answer:
Remove 1 electron
Explanation:
In the atom of each element, there are three subatomic particles viz: proton, neutron and electron. The number of proton (positively charged) and electron (negatively charged) determines the charge of that element. The more the proton, the more positively charged an ion is and vice versa for electron.
According to this question, a neutral atom of lithium (Li) with atomic no. 3 is given i.e. a lithium atom with charge 0. To make the lithium atom's charge change to +1, ONE ELECTRON MUST BE REMOVED OR LOST.
Note that, the proton number (atomic number) of an element does not change, rather the electron number changes in relation to the no. of protons.
pls help name any of these compounds
Answer:
D. Propanol
Explanation:
C3H7OH the presence of alcohol functional group makes it propanol
Which of the following statements accurately describes how a catalyst acts in a chemical reaction?
I. Decreases the kinetic energy of the reaction
II. Is not consumed by the reaction
III. Increases the equilibrium constant
IV. Reduces the required activation energy
a) II, III, and IV only
b) I and III only
c) I and II only
d) II and IV only
Answer:
d) II and IV only.
Explanation:
A catalyst increases the kinetic energy of reactant molecules which increases the magnitude of collision. These then decreases the activation energy . A catalyst is not consumed by reaction because it is neither reactant nor a product, hence has no effect on equilibrium constant.
[tex].[/tex]
Answer:
A
Explanation:
it speed up a chemical reaction without being consumed by the reaction and increases the reaction rate by lowering the activation energy for a reaction but the average kinetic energy of the molecules remains the same well the required energy decreases
(a) (i) What is the name of apparatus used to measure conductivity of water
Answer:
An electrical conductivity meter (EC meter) measures the electrical conductivity in a solution. It has multiple applications in research and engineering, with common usage in hydroponics, aquaculture, aquaponics, and freshwater systems to monitor the amount of nutrients, salts or impurities in the water.
As discussed in class, the Fischer esterification reactants and products are at equilibrium. How was the equilibrium of the reaction that you performed shifted towards the products
Answer:
See explanation
Explanation:
The particular reactants in the Fischer esterification reaction were not stated.
Generally, a Fischer esterification is a reaction that proceeds as follows;
RCOOH + R'OH ⇄RCOOR' + H2O
This reaction occurs in the presence of an acid catalyst.
We can shift the equilibrium of this reaction towards the products side in two ways;
I) use of a large excess of either of the reactants
ii) removal of one of the products as it is formed.
Any of these methods shifts the equilibrium of the Fischer esterification reaction towards the products side.
How many protons does Tin have?
A. 50
B. 68
C. 118
Hello There!
Tin has 50 protons.Hope that helps you!
~Just a felicitous girlie
#HaveASplendidDay
[tex]SilentNature[/tex]
What did Millikan discover
Answer:
Robert Millikan was a physicist who discovered the elementary charge of an electron using the oil-drop experiment
Answer:
the mass of an electron using the Oil-Drop experiment.
Explanation:
A reactant. Q. decomposes at a second order. The slope of the graph 1/[Q] (1/M) vs time (s) is -0.04556. If the initial
concentration of Q for the reaction is 0.50 M, what is the concentration in M. of Q after 10.0 minutes?
Answer:
0.034 M
Explanation:
1/[A] = kt + 1/[A]o
[A] = ?
k= 0.04556
t= 10.0 minutes or 600 seconds
[A]o = 0.50 M
1/[A] = (0.04556 × 600) + 1/0.50
[A] = 0.034 M
Convert 1.25 x 1024 atoms of carbon to moles of carbon.
Answer:
2.076
Explanation:
1 mole is 6.02 * 10^23
To convert from atoms (or molecules or compounds or ions etc.) to mols, you divide the number of atoms (or molecules or etc.) by 6.02 * 10^23
So it is (1.25 * 10^24)/(6.02 * 10^23)
=2.076
Answer:
[tex]\boxed {\boxed {\sf 2.08 \ mol \ C}}[/tex]
Explanation:
We are asked to convert a number of carbon atoms to moles.
We will use Avogadro's Number for this, which is 6.022 × 10²³. This is the number of particles (atoms, molecules, formula units, etc.) in 1 mole of a substance. For this problem, the particles are atoms of carbon. There are 6.022 ×10²³ atoms of carbon in 1 mole of carbon.
We will also use dimensional analysis to solve this problem. To do this, we use ratios. Set up a ratio using the underlined information.
[tex]\frac {6.022 \times 10^{23} \ atoms \ C}{1 \ mol \ C}[/tex]
We are converting 1.25 ×10²⁴ atoms of carbon to moles, so we multiply the ratio by that value.
[tex]1.25 \times 10^{24} \ atoms \ C* \frac {6.022 \times 10^{23} \ atoms \ C}{1 \ mol \ C}[/tex]
Flip the ratio. It remains equivalent, but it allows us to cancel the units atoms of carbon.
[tex]1.25 \times 10^{24} \ atoms \ C* \frac{1 \ mol \ C} {6.022 \times 10^{23} \ atoms \ C}[/tex]
[tex]1.25 \times 10^{24} * \frac{1 \ mol \ C} {6.022 \times 10^{23} }[/tex]
[tex]\frac{1.25 \times 10^{24} } {6.022 \times 10^{23} } \ mol \ C[/tex]
[tex]2.075722351 \ mol \ C[/tex]
The original measurement of atoms has three significant figures, so our answer must have the same. For the number we calculated, that is the hundredths place. The 5 in the thousandths place tells us to round the 7 up to an 8.
[tex]2.08 \ mol \ C[/tex]
1.25 ×10²⁴ atoms of carbon is equal to approximately 2.08 moles of carbon.
For a colligative property such as freezing point depression, :________
a) the charge on the particle affects the property.
b) only the molar mass of the particle matters, not the number of particles.
c) the size of the particle affects the property but not the charge.
d) the number of particles matter but not what they are.
Which is an example of genetic engineering?
A.
humans’ ability to digest cow milk
B.
some bacteria’s resistance to antibiotics
C.
golden rice enriched with vitamin A
D.
lizards with longer legs for surviving floods
Answer:
C. Golden rice enriched with vitamin A
Evaluate the exponential expression (−2)6.
A general exponential expression is something like:
A^n
This means that we need to multiply the number A by itself n times.
Using that we will get (-2)^6 = 64
With that definition, we can rewrite:
(-2)^6 = (-2)*(-2)*(-2)*(-2)*(-2)*(-2)
So we just need to solve the above expression.
Also, remember the rule of signs:
(-)*(-) = (+)
We will get:
(-2)*(-2)*(-2)*(-2)*(-2)*(-2) = [(-2)*(-2)]*[(-2)*(-2)]*[(-2)*(-2)]
= 4*4*4 = 16*4 = 64
Then we got:
(-2)^6 = 64
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If equal moles of boric acid (H3BO3) and NaOH fully react, what species would be in solution at the end of the reaction??
1) H3O+
2) OH-
3) H2BO3-
4) H3BO3
5) OH- and H3O+
The reaction between boric acid and sodium hydroxide is an example of a weak acid strong base reaction.
Boric acid is a weak acid while sodium hydroxide is a strong base.
Having that in mind, we know that a weak acid dissociates only to a small extent in solution while a strong base is almost 100% ionized in solution.
It the follows that a lot of OH- will be left behind after the reaction since only a little fraction of it reacts with the H^+ from boric acid.
Hence, if equal moles of boric acid (H3BO3) and NaOH fully react, OH- is left in the solution after reaction.
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A sentence using the word Compound
Answer:
The air smelled like a compound of diesel and gasoline fumes.
What is an example of an extensive property
1. Consider the following thermochemical reaction for kerosene:
2 C12H26(l) + 37 O2(g) 24 CO2(g) + 26 H2O(l) + 15,026 kJ
(a) When 21.3 g of CO2 are made, how much heat is released?
(b) If 500.00 kJ of heat are released by the reaction, how grams of C12H26 must have been consumed ?
(c) If this reaction were being used to generate heat, how many grams of C12H26 would have to be reacted to generate
enough heat to raise the temperature of 750g of liquid water from 10oC to 90oC?
2. Consider the reaction: NaNO3(s) + H2SO4(l) → NaHSO4(s) + HNO3(g) ΔH° = 21.2 kJ
How much heat must absorbed by the reaction system to convert 100g of NaNO3 into NaHSO4(s)?
3. What is the enthalpy change when 49.4 mL of 0.430 M sulfuric acid reacts with 23.3 mL of 0.309 M potassium
hydroxide?
3.
H2SO4(aq) + 2KOH(aq) → K2SO4(aq) + 2H2O(l) ΔH° = –111.6 kJ/mol
do you have the specific heat for part 2?
What is the amount of heat required to change one mole of a substance from the solid to liquid state known as?
Select the correct answer below:
A) the enthalpy of fusion
B) the melting point
C) the entropy of disorder
D) none of the above
A) the enthalpy of fusion
Explanation:
the heat of vaporization, is the amount of energy needed to change a liquid to a gas at constant temperature and pressure. The energy required to melt a solid to a liquid is called the heat of fusion, and the heat of sublimation is the energy.
Answer:
A
Explanation:
Explain the general properties of aqueous solution based on the following support your answer with examples for each case
1. Electrolytes versus non-electrolyte
2. Precipitation reaction
3. Solubility
An aqueous solution, based on its name, is a water based solution, such that the solvent is water. In such solution, ionic compounds when dissolved, tend to dissociate into the constituent ions, for example, sodium chloride, NaCl forms an aqueous solution of sodium, Na⁺ and chloride, Cl⁻
1) Therefore, aqueous solutions are good electrolyte when ionic, and are therefore, good electrolytes which conduct electricity compared to solids that form non-electrolyte
2) A precipitation reaction is the insoluble product formed by the combination of cations and anions to form ionic solids that are insoluble
3) Aqueous solutions are made with substance that are soluble in water
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Nombre de la siguiente estructura de compuesto orgánico
Answer:
Nombre de la siguiente estructura de compuesto orgánico
Explanation:
The average temperature at the South Pole In January is - 35.4 °C.
Convert this temperature to degrees Fahrenheit. Round your answer to 3 significant digits.
°F
Answer:
-31.72°F
Explanation:
(-35.4°C × 9/5) + 32 = -31.72°F
The average temperature at the South Pole In January is - 35.4 °C. This temperature in Fahrenheit is -31.72 °F
To convert Celsius to Fahrenheit, you can use the formula:
°F = (°C × 9/5) + 32
Let's calculate the temperature at the South Pole in degrees Fahrenheit:
°F = (-35.4 × 9/5) + 32
°F = (-63.72) + 32
°F = -31.72
Rounding to three significant digits, the temperature at the South Pole in degrees Fahrenheit is approximately -31.7 °F. The negative sign indicates that the temperature is below the freezing point in both Celsius and Fahrenheit scales. The South Pole experiences freezing temperatures, as it is located near the Earth's southernmost point and experiences long periods of darkness during January.
Hence, the temperature in Fahrenheit is -31.7 °F.
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#SPJ 4
g Identify the process in which the entropy increases. Group of answer choices a decrease in the number of moles of a gas during a chemical reaction the phase transition from a gas to a liquid the phase transition from a solid to a gas freezing water
Answer:
phase transition from a solid to a gas
Explanation:
Entropy refers to the degree of disorderliness in a system. The more disorderly a system is, the greater the entropy of the system.
Decrease in the number of moles of a gas decreases the entropy of the system. Similarly, the entropy of solids is less than that of liquids. The entropy of liquids is less than that of gases.
Therefore, a change of phase from solid to gas represents an increase in entropy of the system.
Calculate the heat change in calories for melting of 0.30 kg of water at 0*C. The
heat of fusion for water is 80 cal/g. The heat of vaporization of water is 540 cal/g.
The specific heat capacity of water is 1.00 cal/g*C.
Answer: 24 kcal
Explanation:
Given
Mass of water [tex]m=0.3\ kg[/tex]
Temperature of water [tex]T_1=0^{\circ}[/tex]
Heat of fusion [tex]L_f=80\ cal/g[/tex]
Heat of vaporization [tex]L_v=540\ cal/g[/tex]
Specific heat of water [tex]c=1\ cal/g.^{\circ}C[/tex]
Heat require to melt the ice is
[tex]\Rightarrow Q=mL_f\\\Rightarrow Q=0.3\times 1000\times 80\\\Rightarrow Q=24000\ cal\ or\ 24\ kcal[/tex]
Thus, 24 kcal of heat is required to melt 0.3 kg of ice.
What is the difference between elimination and substitution reaction
Identify the key factors that will determine if a reaction undergoes elimination or substitution mechanism.
Use the following reagents to determine the type of reaction pathway expected and determine the products in each reaction.
a. Tert BuO- in tertbutanol and chlorobutane
b. KOH in water and bromobutane
c. NaI in acetone and bromobutane
Write a conclusion of no more than two paragraphs to summarize your results
Answer:
a) E2
b) SN2
c) SN2
Explanation:
A substitution reaction involves replacement of an atom or group in a molecule by another atom or group. An elimination reaction is the loss of two atoms from the same molecule leading to the formation of a multiple bond in the molecule.
We must note that primary alkyl halides never undergo SN1/E1 reactions. However, the presence of a strong bulky base such as tert BuO- , E2 reactions predominate. In the presence of strong bases such as OH^- and good nucleophiles such as I^-, SN2 mechanism predominates.
The following is what kind of reaction?
2 CH4 +4 02 → 2 CO2 + 4H2O
Answer:
It is a combustion reaction.
Gaseous methane (CH4) will react with gaseous oxygen (O2) to produce gaseous carbon dioxide (CO2) and gaseous water . Suppose 2.73 g of methane is mixed with 6.7 g of oxygen. Calculate the maximum mass of water that could be produced by the chemical reaction. Round your answer to significant digits.
Answer:
3.8g of H2O are produced
Explanation:
The balanced reaction of the problem is:
CH4 + 2O2 → CO2 + 2H2O
Where 1 mole of CH4 reacts with 2 moles of O2
To solve this question we need to find, as first, the moles of each reactant in order to find limiting reactant. With limiting reactant we can find the moles of H2O produced and its mass as follows:
Moles CH4 - 16.04g/mol-
2.73g * (1mol/16.04g) = 0.170 moles CH4
Moles O2 -32g/mol-
6.7g (1mol/32g) = 0.209 moles O2
For a complete reaction of 0.170 moles of CH4 are needed:
0.170 moles CH4 * (2 mol O2 / 1mol CH4) = 0.340 moles O2
As there are just 0.209 moles of O2, oxygen is limiting reactant
The moles of water produced are:
0.209 moles O2 * (2mol H2O / 2mol O2) = 0.209 moles H2O
Mass water -Molar mass: 18.01g/mol-
0.209 moles H2O * (18.01g/mol) = 3.8g of H2O are produced
What ion will be formed by the phosphorus atom shown below when it has a stable set of valence electrons?
Phosphorus ion have 3 extra electrons which create a valence of -3.
The correct answer is P3-
Ions combine with other elements and combination in one atom of phosphorus with four atoms of oxygen will create phosphorus ion PO4^3- .
Phosphorus atom has to render 3s electrons to oxygen atom of phosphoryl group.
Phosphorus become positively charged and oxygen becomes negatively charged.
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Heating water makes most solids in it
soluble, and it makes gases
soluble.
Increasing the pressure on a gas above water makes the gas
soluble. Compounds with comparatively stronger ionic bonds are
soluble.
Answer:
1. more
2. less
3. more
4. less
Explanation:
