A negative enthalpy (ΔH)for a molecule means energy was released when the molecule went through a phase change.
What is change in enthalpy (ΔH)?The enthalpy change of a reaction is the amount of heat absorbed or released as the reaction takes place.
Also, the amount of energy required to change the phase of a material is known as the enthalpy,
A negative enthalpy entails the amount of energy released during an exothermic reaction.
Thus, a negative enthalpy (ΔH)for a molecule means energy was released when the molecule went through a phase change.
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Question 2
2C4H10 + 1302 -> 8CO2 + 10H₂O
If 2.46 g H₂O are produced by a reaction, how many moles of C4H10 were used?
Answer:
2 mole of C4H10 were used in this reaction.
The number of moles of Cr deposited by passing 1,5 F electricity in following reaction Cr+3e–– ›cr is
The number of moles of Cr deposited by 1.5 F of electricity is 0.5 moles
What is electrolysis?The term electrolysis has to do with thee deposition of a solid when a direct current is passed through its solution.
Given the reaction; Cr3+(aq) + 3e ––›Cr(s)
If 3F of electricity is required to deposit 1 mole of Cr
1.5F of electricity is required to deposit 1.5F * 1 mole/3F
= 0.5 moles
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Calculate the solubility of Ca(OH)2 in a 0.469M CaCl2 solution at 31°C, given that the Ksp of Ca(OH)2 is 4.96 x 10-6 at that temperature. Give your answer in milliMolar units 2.927 mM 1.626 mM 2.764 mM 1.382 mM 1.463 mM 3.252 mM
The solubility of Ca(OH)2 in a 0.469M CaCl2 solution at 31°C, at given Ksp of Ca(OH)2 is determined as 1.626 mM.
Dissociation reaction of Ca(OH)2
The dissociation reaction of Ca(OH)2 is given as follows;
Ca(OH)₂ ⇄ Ca²⁺ + 2OH⁻¹
x 2x
Concentration of Ca²⁺ = 0.469 M
Ksp = [x][2x]²
ksp = (0.469)(2x²)
ksp = 4(0.469)x²
ksp = 1.876x²
4.96 x 10⁻⁶ = 1.876x²
x² = (4.96 x 10⁻⁶)/(1.876)
x² = 2.643 x 10⁻⁶
x = √(2.643 x 10⁻⁶)
x = 1.626 x 10⁻³ M
x = 1.626 mM
Thus, the solubility of Ca(OH)2 in a 0.469M CaCl2 solution at 31°C, at given Ksp of Ca(OH)2 is determined as 1.626 mM.
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a sample of wood that originally contained 100 grams of carbon14 now contains only 25 grams of carbon 14. approximately how many years ago was this sample part of a living tree
11460 years ago a sample of wood was the part of a living tree.
What is half-life?The time required for half of something to undergo a process.
Carbon-14 has a half-life of 5,730 years. That means that no matter how many carbon-14 atoms were present when something died, after 5,730 years only half of them are left the rest have decayed to nitrogen.
The half life of C-14 is [tex]t_{\frac{1}{2}}[/tex] =5730 years.
This means that if you start with a sample of 100g, only 50g will be left in 5730 years.
Here, Only 25g is left, therefore the number of years is =5730 × 2 = 11460years.
Hence, 11460 years ago a sample of wood was the part of a living tree.
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In the following acid-base reaction
H₂O is the _
HCI(g) + H₂O(l) →H3O*(aq) + Cl-(aq)

Answer: base
Explanation:
The water accepted another hydrogen ion, making it a base.
In the given acid-base reaction, H₂O (water) is the base because it accepts a proton (H+) from the hydrogen chloride (HCl) molecule and forms hydronium ion (H₃O+) by gaining an extra proton.
What is an acid- base reaction ?An acid-base reaction is a chemical reaction in which an acid reacts with a base to form a salt and water. In such a reaction, the acid donates a proton (hydrogen ion) to the base, which accepts the proton. The transfer of a proton from the acid to the base leads to the formation of the conjugate base of the acid and the conjugate acid of the base.
In general, an acid is a substance that donates a proton (H+) and a base is a substance that accepts a proton. When an acid and a base react, the resulting products are a conjugate acid-base pair, where the acid is the product that has gained a proton and the base is the product that has lost a proton.
In the given acid-base reaction, H₂O (water) is the base because it accepts a proton (H+) from the hydrogen chloride (HCl) molecule and forms hydronium ion (H₃O+) by gaining an extra proton.
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The osmotic pressure of an aqueous solution of ammonium phosphate,
(NH4)3PO4 is 11.4 atm at 27 0C. If the density of this solution is 0.854 g/cm3,
calculate the freezing point the solution. Kf for water is 1.86 0C/m
Answer:
the freezeng point of solution is -12°c b/c it dencity is 0.854 formula =
PLEASE HELP!!!!!!!
In an experiment, the molar mass of the compound was determined to be 118.084 g/mol. What is the molecular formula of the compound?
Succinic acid most probably
C_4H_6O_4Lets see why?
The molar mass is given as 118.084g/mol
Decimal next place i.e 10th place contains 0 means it has OH bonds in most of the cases.
So it's a hydrocarbon and more closely an alcohol or aldehyde
Let's verify
4(12)+6(1)+16(4)64+48+670+58118g/molApproximately equal
A container holds a mixture of 3.01 x 1023 molecules of H₂ gas. 1.20 x 1024 molecules of CO₂ gas, and 1.50 x 10
24 molecules O₂. If the total pressure of the container is 1.00atm, what is the partial pressure of oxygen gas in
atmospheres?
O 5.00 x 10 ¹ atm
O 9.09 x 10-2 atm
O2.50 x 10 ¹ atm
O2.00 x 10-¹ atm
8 9
10 11
12 13 14
15 16 1
Answer:
.4998 atm ( rounded to .5 atm ) <===== not one of the answers listed
Explanation:
The partial pressure exerted by O2 is equal to the fraction that is O2 times the pressure
1.5 / ( 1.5 + 1.2 + .301 ) * 1 atm = .4998 atm
( 1) Are you sure it is ONE atm pressure in the container?
(2) IS the first answer supposed to be 5 x 10^-1 atm perhaps?
How is graphite structured?
A. Its carbon atoms are bonded to 3 other carbon atoms and are
structured in layers that can slip past each other.
B. Its carbon atoms are bonded to 3 other carbon atoms and are
structured in layers that cannot slip past each other.
C. Each carbon atom is surrounded entirely by lone pairs, which
is why the carbon atoms separate from each other to the paper
easily when writing.
D. Each carbon is bonded to four others making it very solid and
rigid.
Graphite is structured in a way that: (A). Its carbon atoms are bonded to 3 other carbon atoms and are structured in layers that can slip past each other.
Meaning of a graphiteA graphite can be defined as a crystalline form of carbon.
Graphite is so important to man as it is used in many industries and factories as well as many countries to produce different products that can help mankind.
Graphite structure is quite a complex one and it involve carbons that have three of its electrons bonded and one free.
In conclusion, Graphite is structured in a way that: Its carbon atoms are bonded to 3 other carbon atoms and are structured in layers that can slip past each other.
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What volume of 12M HCI is needed to prepare 250
of 0.20M HCI?
Answer: 4.2
Explanation:
[tex]M_{A}V_{A}=M_{B}V_{B}\\(12)V_{A}=(250)(0.20)\\V_{A}=\frac{(250)(0.20)}{12}=\boxed{4.2}[/tex]
Two moles of gas A spontaneously convert to 3 moles of gas b in a container where the temperature and pressure are held constant. The sample originally took up 13.9L of volume. What is the new volume of the products? Pls show work :)
At constant temperature and pressure, If the amount of gas increases to the given value, its volume also increases to 20.85L.
What is Avogadro's law?Avogadro's law states that "equal volumes of all gases, at the same temperature and pressure, have the same number of molecules."
It is expressed as;
V₁/n₁ = V₂/n₂
Given the data in the question;
Initial amount of gas n₁ = 2molesInitial volume v₁ = 13.9LFinal amount of gas n₁ = 3molesFinal volume v₂ = ?V₁/n₁ = V₂/n₂
V₁n₂ = V₂n₁
V₂ = V₁n₂ / n₁
V₂ = (13.9L × 3moles) / 2moles
V₂ = 41.7molL / 2mol
V₂ = 20.85L
At constant temperature and pressure, If the amount of gas increases to the given value, its volume also increases to 20.85L.
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Which of the following items represents a chemical change?
melting
evaporation
freezing
burning
What is the equilibrium constant of a reaction?
A. It is the concentrations of products multiplied by the
concentrations of reactants.
о
B. It is the number of moles of reactants subtracted from the number
of moles of products.
C. It is the ratio of the concentrations of products to the
concentrations of reactants.
D. It is the ratio of the number of moles of products to the number of
moles of reactants.
Answer:
C. It is the ratio of the concentrations of products to the
concentrations of reactants.
Explanation:
please please helpppp
if someone could give me the answer on how to balance this equation with explanation that would be great.
Ag2O → Ag + 0₂
thanks in advance
Describe a chemical test for water-
Answer:
Anhydrous copper (II) sulphate is white because it has no water in it. When drops of water are added, copper (II) sulphate turns blue. This colour change can be used to detect the presence of water (or water vapour).
What will happenhappen to the pressure of a gas if its Container's volume decreases .
Answer: The pressure will increase.
Explanation:
Boyle's law states that "the volume of a gas at constant temperature varies inversely with the pressure exerted on it." In other words, if there is more volume for the gas to spread, the pressure will decrease.
This also goes the opposite way, meaning with less volume the pressure will increase.
Which of these is NOT true about electromagnets?
They are permanent.
Increasing the battery makes them stronger.
They need a battery or other source of current.
Increasing the number of coils makes them stronger.
Answer:
Permanent = false
Explanation:
All of the other choices are true
Given that this reaction is exothermic, what direction will the equilibrium shift when the temperature of the reaction is decreased? 3H₂(g) + N₂(g) ⇔ 2NH₃(g)
A. Left (towards the reactants)
B. Right (towards the products)
C. No Shift
Equilibrium will shift towards the products when temperature is decreased in an exothermic reaction of the formation of ammonia.
What is an exothermic reaction?An exothermic reaction is a reaction in which heat content of the reactants is greater than the heat content of product.
In an exothermic reaction, heat is given off.
For an exothermic reaction in equilibrium, increasing temperature shifts equilibrium to the towards the left, towards the reactants.
On the other, equilibrium will shift towards the products when temperature is decreased.
Therefore, equilibrium will shift towards the products when temperature is decreased in the reaction of the formation of ammonia.
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How many moles are in 2.372e+02 mg (milligrams) of bromic acid?
Answer:
1.840 x 10⁻³ mol HBrO₃
Explanation:
To find the moles of bromic acid (HBrO₃), you should (1) convert milligrams to grams (by dividing by 1,000) and then (2) convert moles to grams (via molar mass from periodic table).
Molar Mass (HBrO₃): 1.008 g/mol + 79.904 g/mol + 3(15.998 g/mol)
Molar Mass (HBrO₃): 128.906 g/mol
2.372 x 10² mg HBrO₃ 1 g 1 mole
---------------------------------x----------------x------------------ = 1.840 x 10⁻³ mol HBrO₃
1,000 mg 128.906 g
when we send electricity to pass through electrolysis jar we see gas bubble around both electrodes. Water electrolysis produces 46cm3 at anode.
A). What gas does it appear at each electrode?
B). What would you do to identify the gas in the test tubes at each electrode?
C). Calculate the volume of gas which appears at cathode.
A) Anode - hydrogen gas
Cathode-oxygen gas
B) Hydrogen gas - The gas burns with a pop sound
Oxygen gas - The gas rekindles a glowing splint
C) The volume of gas produced at the cathode is 23 [tex]cm^3[/tex]
What is electrolysis?Electrolysis is the process by which electric current is passed through a substance to effect a chemical change.
The electrolysis of water produces two volumes of hydrogen at the anode and one volume of oxygen at the cathode.
The hydrogen gas burns with a pop sound. It is easily identified by this test. Also, oxygen is known to rekindle a glowing splint and this is a commonly used test for oxygen gas.
Since the ratio of hydrogen produced at the anode to oxygen produced at the cathode is 2:1 by volume; then when 23 [tex]cm^3[/tex] of oxygen is produced at the cathode, 46 [tex]cm^3[/tex]of hydrogen is produced at the anode.
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Can anyone please help me, the attachment is down below
Bubbling or fizzing is usually observed when a chemical reaction occurs and is denoted as option D.
What is a Chemical reaction?This occurs when one or more reactant form a new substance which is referred to as the product.
The bubbling or fizzing depicts effervescence which signifies that a new gaseous product has been formed.
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An air mattress is filled with 0.55 moles of air. The air inside the mattress has a temperature of 295 K and an absolute pressure of 3.5 kilopascals. What is the volume of the air mattress?
The volume of the air mattress is
liters.
The volume of the air mattress in litres is 385 litres when absolute pressure was 3.5 kilopascals.
What is an ideal gas equation?The ideal gas law (PV = nRT) relates to the macroscopic properties of ideal gases. An ideal gas is a gas in which the particles (a) do not attract or repel one another and (b) take up no space (have no volume).
Given data:
P= 3.5 kPa
V=?
n= 0.55 moles of air
T= 295K
R= 8.314 (L kPa/mol K)
We use the constant rate of 8.314 because we are using kilopascals in this problem.
Using the equation:
PV=nRT,
V = [tex]\frac{0.55 \;moles \;X \;8.314 \;L \;k\;Pa/mol k \;X \;295 K}{3.5 \;kPa}[/tex]
V = 385.4132857 L.
Hence, the volume of the air mattress in litres is 385 litres.
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Do taller people have longer arms that shorter people? Find the dependent variable, independent variable and state your hypothesis. PLS HELP
Answer:
A hypothesis is a testable statement that is proposed to explain an observation/theory. In this case, one hypothesis that could be used is: Taller people have longer arms than smaller people. You could also say: As the height of an individual increases, the length of their arms also increases.
Independent variables are the variable that is manipulated. In this case, the independent variable is the height of the individual.
Dependent variables are those that change in response to the independent variable. In this case, the dependent variable is arm length.
Use the reaction and bond information to answer the question. H2 CO2 → CH2O2 Reactant bond energies: H–H is 432 kJ/mol, C=O is 799 kJ/mol Product bond energies: C–H is 413 kJ/mol, C=O is 745 kJ/mol, C–O is 358 kJ/mol, O–H is 467 kJ/mol How much energy must this system absorb before the reaction can begin?.
345678990098765435779999999999999999995699999
A 47-year-old man with a history of alcoholism is brought to the emergency department because he was found wandering in the streets. He appears disoriented and walks unsteadily. Physical examination shows an inability to adduct the right eye or to abduct the left eye. When asked about recent events that may have resulted in his condition, he responds with several elaborate but obviously fictitious stories. Altered activity of which of the following enzymes is most likely contributing to his symptoms?
The altered activity of the Pyruvate dehydrogenase enzyme is most likely contributing to his symptoms.
What is Pyruvate dehydrogenase?Pyruvate dehydrogenase is an enzyme that catalyzes the conversion of pyruvate to generate dihydrolipoamide and CO2.
This enzyme (Pyruvate dehydrogenase) is required to metabolize alcohol present in the blood.
In conclusion, the altered activity of the Pyruvate dehydrogenase enzyme is most likely contributing to his symptoms.
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Convert 3.80 mol of KCI to grams?
Answer:
283 grams KCl
Explanation:
To convert form moles to grams, you need to find the molar mass of your compound. The molar mass can be calculated using the individual molar masses of each element in the compound. These values can be found on the periodic table.
Molar Mass (K) = 39.098 g/mol
Molar Mass (Cl) = 35.453 g/mol
Molar Mass (KCl) = 39.098 g/mol + 35.453 g/mol
Molar Mass (KCl) = 74.551 g/mol
Now that you know the molar mass, you want to multiply it by the moles of KCl. This is possible because the molar mass is actually a ratio representing the relationship of grams and moles. In KCl, there are 74.551 grams of KCl for every 1 mole of KCl. When you are multiplying, make sure you set the ratio up in a way that allows for the units to cancel out and leave grams as your final answer.
3.80 moles KCl 74.551 g
----------------------- x ------------------- = 283 grams KCl
1 mole KCl
The final answer should have 3 sig figs because the value the problem gave (3.80 mol) also has 3 sig figs.
How dose earths solid inner core affect seismic waves
Answer:
When seismic waves from earthquakes ripple through its solid center, they hit a speed bump. The seismic vibrations should zip along about 30 percent faster than their actual speed, according to experiments and computer models re-creating the conditions inside the inner core.
What is the formula for the carboxylic acid functional group?
OA. -CH3
OB. -COH
0 с. -соон
OD. -CO-
Answer: C
Explanation:
This is a fact.
What is the heat of reaction into kJ?
H₂(g)+Br₂(g)➝2HBr(g)
see the attached file!!!
What is specific heat capacity?
If answer is correct I will mark as brainliest
Answer:
A. The energy required to completely melt 1 g of a substance.
Explanation:
Because the root definition for Specific Heat Capacity is basically the amount of heat that's absorbed per unit mass of whatever material when the temperature is increasing. Or in other words, the amount of heat that's taken out or supplied to the unit mass of a system in order to increase or decrease its temperature by one degree. Hope this helps :)