Answer: The enthalpy of the reaction is -1791.31 kJ.
Explanation:
Enthalpy change is the difference between the enthalpies of products and the enthalpies of reactants each multiplied by its stoichiometric coefficients. It is represented by the symbol [tex]Delta H^o_{rxn}[/tex]
[tex]\Delta H^o_{rxn}=\sum (n \times \Delta H^o_{products})-\sum (n \times \Delta H^o_{reactants})[/tex] .....(1)
For the given chemical reaction:
[tex]3MnO_2(s)+4Al(s)\rightarrow 2Al_2O_3(s)+3Mn(s)[/tex]
The expression for the enthalpy change of the reaction will be:
[tex]\Delta H^o_{rxn}=[(2 \times \Delta H^o_f_{(Al_2O_3(s))}) + (3 \times \Delta H^o_f_{(Mn(s))})] - [(3 \times \Delta H^o_f_{(MnO_2(s))}) + (4 \times \Delta H^o_f_{(Al(s))})][/tex]
Taking the standard heat of formation values:
[tex]\Delta H^o_f_{(Al_2O_3(s))}=-1675.7kJ/mol\\\Delta H^o_f_{(Al(s))}=0kJ/mol\\\Delta H^o_f_{(MnO_2(s))}=-520.03kJ/mol\\\Delta H^o_f_{(Mn(s))}=0kJ/mol[/tex]
Plugging values in the above expression:
[tex]\Delta H^o_{rxn}=[(2 \times (-1675.7))+(3 \times 0)] - [(3 \times (-520.03))+(4 \times 0)]\\\\\Delta H^o_{rxn}=-1791.31 kJ[/tex]
Hence, the enthalpy of the reaction is -1791.31 kJ.
Describe the formation of calcium chloride (4 marks)
Answer:
It is an ionic compound that consists of one calcium cation Ca2+ and two chlorine anions. The bivalent calcium metal forms an ionic bond with two chlorine atoms. The formation of cacl2 happens mainly by reacting limestone (CaCo3) with hydrochloric acid (HCl).
The table below gives some characteristics of element Y.
Characteristics of element Y Values
Mass number 11
Number of neutrons in a single atom 6
Average atomic mass (grams/mole) 10.81
What is the identity of element Y?
Answer:
Boron B
Explanation:
According to the periodic table, Boron is the element with atomic mass of approximately 11 [i.e 10.81]
To calculate Neutrons
Neutrons = Mass number - Protons
Number of protons in Boron is same as atomic number which is 5
Thus, N = 11 - 5 = 6
Which of the following pairs of elements is most likely to form an ionic compound?
• magnesium and sodium
• nitrogen and sulfur
• oxygen and chlorine
• magnesium and chlorine
• carbon and fluorine
Explanation:
magnesium and sodium because they are minerals and part of iron
What is a natural disaster?
Answer:
Explanation:
A natural disaster is a major adverse event resulting from natural processes of the Earth; examples include floods, hurricanes, tornadoes, volcanic eruptions, earthquakes, tsunamis, storms, and other geologic processes
Answer:
A natural disaster is a natural, major harmful event resulting from natural processes of the Earth such as floods, earthquakes, or hurricanes, tornadoes, volcanic eruptions, tsunamis, storms, and other geologic processes that causes great damage or loss of life.
How many centimeters are in 5 miles? Hint: 1 miles = 5280 feet
Calculate the standard enthalpy change for the reaction 2A+B⇌2C+2D Use the following data: Substance ΔH∘f (kJ/mol) A -235 B -413 C 193 D -493
Answer:
ΔH = 283kJ/mol
Explanation:
Using Hess's law, the ΔH of a reaction is equal to the sum of ΔH° of products times its coefficient subtracting the sum of ΔH° of reactants times its coefficient. Replacing, for the reaction:
ΔH = 2ΔH°C + 2ΔH°D - (2ΔH°A+ΔH°B)
ΔH = 2*193kJ/mol + 2*-493kJ/mol - (2*-235kJ/mol+ (-413kJ/mol)
ΔH = 283kJ/molLime is added to a lake to neutralize the effects of acid rain. The pH value of the
lake water rises from 4 to 7. What is the change in concentration of H+ ions in the
lake water?
Answer:
The change in concentration of H+ ions is -9.99×10⁻⁵
Explanation:
When pH rises, we talk about neutralization and, there is a decline in proton's concentration.
pH lower than 7 is acid
pH higher than 7 is basic
Protons are neutralized by hydroxides to make water as this:
H₃O⁺ + OH⁻ ⇄ H₂O
pH = - log [H₃O⁺]
[H₃O⁺] = 10^-pH
In conclussion: [H₃O⁺]₁ = 10⁻⁴ → 1×10⁻⁴
[H₃O⁺]₂ = 10⁻⁷ → 1×10⁻⁷
1×10⁻⁷- 1×10⁻⁴
The change in concentration of H+ ions is -9.99×10⁻⁵
what is neutralisation reaction? why is it named so? give one example.
Answer:
In chemistry, neutralization or neutralisation is a chemical reaction in which acid and a base react quantitatively with each other. In a reaction in water, neutralization results in there being no excess of hydrogen or hydroxide ions present in the solution.Neutralization reactions are the reaction between acid and base. The products formed are water and salt. It is called so because the acid and base neutralize each other to form water and salt.Hint: The neutralization reaction is the one in which an acid reacts with an equimolar amount of base to give salt and water. The example could be a reaction between any strong acid and a base. The sodium chloride formed is a result of neutralization reaction.
Trust me mark me as brainliest trust me
Why don’t scientists use the Bohr model above to explain charge transfer?
Answer:
nsksbsjensnsjeiejensbsksks
The electronegativities of carbon and sulfur are almost the same. Both elements form covalently bonded compounds with hydrogen. Why is hydrogen sulfide a polar compound while methane is a nonpolar compound?
a.Sulfur has a stronger attraction for electrons than does carbon
b.A hydrogen sulfide molecule has lone pairs of electrons
c.Sulfur forms ionic bonds with hydrogen while carbon forms covalent bonds
d.Sulfur ions are larger than carbon ions
Answer:
b. A hydrogen sulfide molecule has lone pairs of electrons
Explanation:
The presence of lone pairs indictates that the molecule will be polar unless its molecular geometry is linear or square planar. In the case of H2S, its shape is bent due to the lone pair and it is a slightly polar molecule.
A doctor is testing a new medication and he doesn’t tell the people in the study about the possible side effects of the medicine. He is _____.
How do countries with different currencies trade goods with each other?
A.
They trade actual physical products to avoid confusion over currency differences.
B.
They negotiate to determine which country's currency will be used for the whole exchange.
C.
They create a new shared currency, such as the European Union countries' euro.
D.
They use the exchange rate to convert one country's currency to another's.
Answer:
D- They use the exchange rate to convert one's Country's currency to another's
Explanation:
What is the empirical formula of a compound containing 5.03 g carbon, 0.42 g hydrogen, and 44.5 g of chlorine
Answer:
CHCl₃
Explanation:
We have the following data:
C = 5.03 g
H = 0.42 g
Cl= 44.5 g
First, we divide each mass by the molar mass (MM) of the chemical element to calculate the moles:
MM(C) = 12 g/mol
moles of C = mass/MM(C) = 5.03 g/(12 g/mol) = 0.42 mol C
MM(H) = 1 g/mol
moles of H = mass/MM(H) = 0.42 g/(1 g/mol) = 0.42 mol H
MM(Cl) = 35.4 g/mol
moles of Cl = mass/MM(Cl) = 44.5 g/(35.4 g/mol) = 1.26 mol Cl
Now, we divide the moles by the smallest number of moles (0.42):
0.42 mol C/0.42 = 1 C
0.42 mol H/0.42 = 1 H
1.26 mol Cl/0.42 = 3 Cl
Thus, the C:H:Cl ratio is 1:1:3.
Therefore, the empirical formula is CHCl₃
Answer:
CHCl₃
Explanation:
Hydrogen and nitrogen react to form ammonia. The chemical equation for this reaction is shown here. 3 H2(g) + N2(g) 2 NH3(g). What amount of hydrogen will produce 44.0 mol of ammonia?
66.0 mol
88.0 mol
132.0 mol
29.3 mol
Answer:
someone already answered but i think it's 132.0 mol too
An apple has been left out, and it is starting to rot. Which of the following is the best method to slow down the chemical changes that are occurring?
The best method is to keep rinsing the apple with water every hour.
The best method is to keep the apple in a cooler place.
The best method is to put the apple in the sun to warm it up.
The best method is to wrap the apple in plastic.
What is the general form of a synthesis reaction?
O A. AB + CD → AC + BD
B. A + B → AB
O C. AB + C → AC + B
D. AB → A+B
Be
The answer is B
Answer:
B. A+ B → AB
Explanation:
general form of a synthesis reaction
A compound being used in experimental medicine is 78.14% boron (B) and 21.86% hydrogen (H). The empirical formula of the compound will have a boron to hydrogen ratio of
Explanation:
I did it step by step so It would be easier to understand:)
Chloe’s teacher gives her and her lab partner soil samples from different parts of the city: the park, the area next to a pond, the school, and a neighborhood. Chloe’s teacher also gives her a soil tester kit, which determines the pH of the soil. Chloe and her lab partner need to determine the pH of each soil sample and then compare them.
Fill in the blank with the word that best completes the statement.
This investigation is a(an)______investigation.
Answer:
an
Explanation:
It is AN because investigation starts with I ( i is a vowel). When there are vowels we use An.
Pls mark me brainliest!
Question 14 of 30
Which of the following elements has 1 valence electron?
The Periodic Table
A. Sodium (Na)
B. Chlorine (CI)
C. Calcium (Ca)
D. Helium (He)
SUBMIT
Answer:
A. Sodium (Na)
Explanation:
The total number of electrons in the outermost principal energy level of an element is called the valence electrons of that element.
Na (11)---→1s2 2s2 2p6 3s1
There 1 electron in the outermost principal energy level of Sodium. So, the number of valence electron of Sodium is 11.
Answer:
Na
Explanation:
I was learning about it recently, that dude's right, it's Sodium
Which substance is a binary acid?
hydrochloric acid
phosphoric acid
nitrous acid
sulfuric acid
Answer:
A) Hyrdrochloric Acid
Explanation:
This is because binary acids are molecular compounds in which hydrogen is combined with a non-metal element. Hydrochloric acid has hydrogen present in it's compound, therefore identifying it as the only binary acid amongst the answer choices.
any of ya'll good at chemistry?????
Answer:
i good at chemistry
Explanation:
not all but i try
why do objects cool down
Answer:
wla dyan ang sagut ehh baka mali yan
Which of the following statements regarding carbon is false? Group of answer choices Carbon has the capacity to form single and double bonds. Carbon has the ability to bond with up to six other atoms. Carbon has a tendency to form covalent bonds. Carbon has the ability to bond together to form extensive branched or unbranched "carbon skeletons."
Answer: The statement, carbon has the ability to bond with up to six other atoms is false.
Explanation:
Carbon is a group 14 element and it is a non-metal. The atomic number of carbon is 6 and its electronic distribution is 2, 4.
This means that there are 4 valence electrons present in it. Also, in order to attain stability a carbon atom forms only covalent bonds, that is, it shares its valence electrons with its own atoms or atoms of other elements.
Carbon has the capacity to form single and double bonds.
As valency of carbon is four so it can only combine to 4 other atoms vis single bond and it cannot bond with up to six other atoms.
Carbon shows the property of catenation, that is, it forms covalent bonds with its own atoms in a large number. So, carbon has the ability to bond together to form extensive branched or unbranched "carbon skeletons".
Thus, we can conclude that the statement, carbon has the ability to bond with up to six other atoms is false.
what are the characteristics or properties that you can use to classify elements
Answer:
The number of outermost energy level electrons ( valency electrons )
The atomic number
Valence electrons are important when drawing molecular structures because
a. They are closest to the nucleus of the atom and do not participate in chemical
bonding
b. They are closest to the nucleus of the atom and participate in chemical
bonding
c. They are farthest away from the nucleus of the atom and do not participate in
chemical bonding
d. They are farthest away from the nucleus of the atom and participate in
chemical bonding
Answer:
d
Explanation:
Valence electrons are in the outermost shell. They form chemical bonds with other elements, not any other electrons. Hope this helps!
what's the chemical formula for salt, like is it NaCl??
the salt we eat???????
yeah it's NaCl, I just looked it up
Answer:
Yes
Explanation:
NaCl is table salt
Also known as sodium chloride
what is an earthquake's epicenter found
Answer:
an epicenter is where an earthquake first hit
Answer:
The epicenter
Explanation:
The location below the earth's surface where the earthquake starts is called the hypocenter, and the location directly above it on the surface of the earth is called the epicenter. ... These are smaller earthquakes that occur afterwards in the same place as the mainshock.
Which statement about the mass of an electron is correct? A The mass of an electron is equal to the mass of the proton. B The mass of an electron is less than the mass of the proton. с The mass of an electron is equal to the mass of a neutron. D The mass of an electron is greater than the mass of a neutron.
Answer:
B
Explanation:
because mass of an electron is 1/2000.
The statement about the mass of an electron which is correct is: B. The mass of an electron is less than the mass of the proton.
An atom refers to a smallest, indivisible unit that comprises the matter that forms all chemical elements. Therefore, atoms are typically considered as the fundamental building blocks of matter which determines the structure of a chemical element.
Basically, an atom consists of three (3) distinct particles and these include;
Protons. Neutrons. Electrons.
Electrons are the subatomic particles of a chemical element that are negatively charged with a magnitude of -1.
On the other hand, protons can be defined as the subatomic particles of a chemical element that are positively charged.
All of these subatomic particles of a chemical element has a mass. However, the mass of an electron is significantly less than the mass of proton, as a result of its extremely small size.
In conclusion, the mass of an electron is approximately 2000 times smaller than that of a proton and as such contributes almost nothing to the total mass of an atom.
Find more information: https://brainly.com/question/18214726
What is the limiting reactant in a reaction where 10.0 mol of iron is treated with 12.0 mol of bromine? The product that forms is FeBr3. First, write and balance the chemical equation. Next, calculate the moles of FeBr3 that can be made from 10.0 mol of Fe. Then calculate the moles of FeBr3 that can be made from 12.0 mol of bromine. The smaller amount of FeBr3 reveals the limiting reactant.
Answer: The limiting reagent in the reaction is bromine.
Explanation:
Limiting reagent is defined as the reagent which is completely consumed in the reaction and limits the formation of the product.
Excess reagent is defined as the reagent which is left behind after the completion of the reaction.
Given values:
Moles of iron = 10.0 moles
Moles of bromine = 12.0 moles
The chemical equation for the reaction of iron and bromine follows:
[tex]2Fe+3Br_2\rightarrow 2FeBr_3[/tex]
By the stoichiometry of the reaction:
If 3 moles of bromine reacts with 2 moles of iron
So, 12.0 moles of bromine will react with = [tex]\frac{2}{3}\times 12.0=8moles[/tex] of iron
As the given amount of iron is more than the required amount. Thus, it is present in excess and is considered as an excess reagent.
Hence, bromine is considered a limiting reagent because it limits the formation of the product.
Thus, the limiting reagent in the reaction is bromine.
How many atoms are in 9.8 moles of NaCl?
Answer:
a lot but im pretty sure if u just take avogadros number and multiply it by 9.8 u get the answer
Explanation:
There are 5.89 × 10²⁴ atoms in 9.8 moles on NaCl. Details about number of atoms can be found below.
How to calculate number of atoms?The number of atoms of a compound can be calculated by multiplying the number of moles of the substance by Avogadro's number.
no of atoms = no of moles × 6.02 × 10²³
According to this question, there are 9.8 moles of NaCl.
no of atoms = 9.8 × 6.02 × 10²³
no of atoms = 5.896 × 10²⁴
Therefore, there are 5.89 × 10²⁴ atoms in 9.8 moles on NaCl.
Learn more about number of atoms at: https://brainly.com/question/8834373
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