The standard enthalpy change associated with the given reaction at 25 °C using the following enthalpies of formation will be − 902.4 kJ
What is Standard Enhalpy change ?The standard enthalpy change of formation of a compound is the enthalpy change which occurs when one mole of the compound is formed from its elements under standard conditions, and with everything in its standard state.
According to the balanced chemical equation ;
CH₄(g) + 2O₂(g) ⟶ CO₂(g) + 2H₂O(l)
Now,
ΔH⁰ = ΔH⁰f(products) − ΔH⁰f(reactants)
= [ΔH⁰(CO₂) +ΔH⁰(H₂O)] − [ΔH⁰(CH₄) + 2ΔH⁰(O₂)]
= [−393.5 + 2 x (−285.8)] − [−62.7 + 2 x 0]
= − 902.4 kJ
Hence, The standard enthalpy change associated with the given reaction at 25 °C using the following enthalpies of formation will be − 902.4 kJ
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Choose the correct option.
1. A chain of small chemical units combined to form a large single unit is called ______
a) Polymer
b) Poly
c) Polythene
d) None of the above
2. Polythene and PVC are examples of
a) Bio degradable substance
b) Thermosetting plastics
c) Thermoplastics
d) Rayon
3. Plastics which when moulded once, cannot be softened by heating. Such plastics are called __ a) Polythene
b) Thermoplastics
c) Polyster
d) Thermosetting plastics
4. Polycot is made by mixing two types of fibres namely
a) Silk + Cotton
b) Polythene + cotton
c) Silk + Polyester
d) Polyester + Cotton
5. The 4 R Principle is
a) Reduce, Reuse, Recycle, Recover
b) Remember, reduce, Recycle, Rejoice
c) Repeat, Rejoice, recycle, reduce
d) None of the above
6. _____________ is an example of natural polymer
a) Rayon
b) Cellulose
c) Nylon
d) All of the above
7. Which of the following is Non-biodegradable ?
a) Woolen clothes
b) Plastic bag,
c) Cotton cloth
d) Wood
8. Bakelite and Melamine are examples of
a) Thermosetting plastics
b) Silk
c) Nylon
d) Rayon
9. Fire proof plastic uniform worn by fire fighters has a coating of _____ to make it fire resistant. a) Nylon
b) Rayon
c) Melamine plastic
d) silk
The coating on modern non- stick cookware and electric iron is of
a) Terrycot
b) Rayon
c) Polyester
d) Teflon
Question 26 of 30
For a reaction, AH = -75 kJ/mol and SO = -0.081 kJ/(K.mol). At what
A
temperatures is this reaction spontaneous?
O A. T<930 K
OB. At all temperatures
C. T< 100 K
OD. T> 930 K
Answer: B
Explanation:
The average atomic mass of carbon is 12.01 amu. Based on the atomic
masses of the two isotopes of carbon, how do the relative abundances of the
isotopes compare?
Isotope
Atomic mass (amu)
C-12
12.000
C-13
13.003
OA. There is a slightly larger percentage of C-12 than C-13.
OB. There is a very large percentage of C-12.
OC. There is a very small percentage of C-12.
OD. They are about the same.
Answer: There is a very large percentage of C-12.
Explanation:
The atomic mass is must closer to that of C-12 than of C-13, meaning that there is a much larger percentage of C-12.
Question 21
A sample of rainwater has a pH of 3.5. What ion is sure to be present in relatively
large concentration in this rain sample?
H3O+
SO4²-
OH
HSO4
A sample of rainwater with a pH of 3.5 is sure to contain a large concentration of [tex]H_3O^+[/tex]
pH scaleA pH value of 7 downward is said to be acidic. Upward of 7 is said to be basic. A pH of 7 on the dot is said to be neutral.
An acid is defined as a substance that produces [tex]H_3O^+[/tex] as its only positively charged ion in solution.
Thus, rainwater with a pH of 3.5 is acidic and will contain a high concentration of [tex]H_3O^+[/tex].
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Identify the products formed in this Brønsted-Lowry reaction.
HCO−3+BrO−↽−−⇀acid+base
Answer:
HCO3- + BrO- → HBrO + CO32-
Explanation:
I think this is the answer hope it helps
A piece of metal with a mass of 23.2 g at 120.1oC is placed in a styrofoam cup containing 35.0 g of water at 22.2oC. Once the system has reached equilibrium, the final temperature of the water is 34.0oC. What is the specific heat of the metal to four significant digits? The specific heat of water is 4.18 J/g-oC.
Answer:
0.8797 J/g oC
Explanation:
use mcAT=mcaT
37) Which chemical equation is correctly balanced?
a) Al(OH)3(s) → Al₂O3(s) + 2 H₂O(g)
b) KI(aq) + Pb(NO3)2(aq) → KNO3(aq) + 4 Pbl₂(aq)
c) 2 Na3PO4(aq) + 3 CaCl₂(aq) →6 NaCl(aq) + Ca3(PO4)2(aq) to S
d) CsH12) +6 O₂(g)→ 5 CO₂(g) + 6 H₂O(g)
0 (0
Answer: c) [tex]2\text{Na}_{3}\text{PO}_{4}+3\text{CaCl}_{2} \longrightarrow 6\text{NaCl}+\text{Ca}_{3}\text{(PO}_{4})_{2}[/tex]
1. A balloon contains 100g of oxygen gas (O₂) when the volume is 110 dm³. Find the volume of the balloon when the mass of oxygen gas is decreased to 50g. [take O=16] 1. A balloon contains 100g of oxygen gas ( O₂ ) when the volume is 110 dm³ . Find the volume of the balloon when the mass of oxygen gas is decreased to 50g . [ take O = 16 ]
The volume of the balloon when the mass of oxygen gas is decreased to 50g is 50L.
We will use the ideal gas equation-
PV=nRT
P=Pressure
V=volume
n=no. of moles
T=temperature
In this question temperature and pressure will remains constant then the above equation can be rewritten as-
[tex]V_{1} /n_{1} =V_{2} /n2[/tex]
where V1= initial volume of the balloon
V2= volume of the balloon when the mass of oxygen gas is decreased to 50g
now, substitute the values in the above equation-
V1=100dm3=100Ln1=100/32=3.12n2=50/32=1.56100/3.12=V2/1.56
V2=50 Lhence, the volume of the balloon when the mass of oxygen gas is decreased to 50g is 50L.
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How many atom are present in a piece of iron that has a mass of 65.
0g
Iron has an atomic mass of 55.845 g/mol, so the amount of iron in 65.0 g is 65.0/55.845 = mol.
Avogadro's law states that in every mole of a substance, there are [tex]6.022 \times 10^{23}[/tex] particles per mole, so in this case, that means there are [tex](1.16393589)(6.022 \times 10^{23})=\boxed{7.01 \times 10^{23}} \text{ atoms (to 3 sf)}}[/tex]
Calculate the moles for C. and D. in the attached picture:
The moles of nitrogen (iv) oxide produced in C and D are 0.284 moles and 68.32 moles respectively.
What is the mole ratio of the reaction?The mole ratio of the given reaction shows that 2 moles of dinitrogen (v) oxide produces 4 moles of nitrogen (iv) oxide when it decomposes.
B of dinitrogen (v) oxide in 15.4 g is calculated below:
Molar mass of dinitrogen (v) oxide = 108 g/mol
Moles of dinitrogen (v) oxide = 15.4/108 = 0.14 moles
Moles of nitrogen (iv) oxide produced = 0.142 * 2 = 0.284 moles
Moles of dinitrogen (v) oxide in 3.69 kg is calculated below:
Molar mass of dinitrogen (v) oxide = 108 g/mol
Mass = 3.69 kg = 3690 g
Moles of dinitrogen (v) oxide = 3690/108 = 34.16 moles
Moles of nitrogen (iv) oxide produced = 34.16 * 2 = 68.32 moles
Therefore, the moles of nitrogen (iv) oxide produced in C and D are 0.284 moles and 68.32 moles respectively.
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How many taste buds are present on the tongue? Name them.
there are five Taste bud present tongue they are -
SWEET SALT SOUR BITTER UMAMI ______________________out of the four type of papillie present on tongue the fungiform circumvallate and folite papillie contain numerous small taste but few such type of Taste but also occur in the mucous membranes of soft palate tonsils and epiglottis all of these days but received taste is normally
each Taste bud is an oval structures formed due to modification of epithelial cells which are situated erect and vertically on the surface long sensory cells and supporting cells are found in this bird is sensory cell is spindle shaped in which a sensory here is found at its free in the century fibre of the facial and vagus cranial nerves are wrapped around the basal and of the gustatory cells each test but open on the epithelial surface through minute taste pore
____________________Help please! Thank you!
Answer:
KCl
Explanation:
Ionic compounds are formed between atoms with very different electronegativity (EN) values. The elements with the highest EN values are on the top-right of the periodic table.
Ionic compounds are also generally between a metal and nonmetal. Nonmetals are located in the p-block (the right) of the periodic table and metals are pretty much everywhere else.
That being said, water (H₂O), CO, and CO₂ contain elements that have too similar of EN values to ionically bond.
However, the elements in KCl have different enough EN values to undergo ionic bonding by donating/receiving electrons from each other.
What is the percent yield for the reaction below when
705.0 g SO2 and 80.0 g 0₂ produce 586.0 g SO3?
2SO2(g) + O₂(g) → 2SO3(g)
The percent yield for the chemical reaction producing sulfur trioxide is 66.51%.
What is percent yield?Percent yield is defined as the ratio of actual yield to the theoretical yield multiplied by 100. If the actual and theoretical yield are same then the percent yield is 100%.If actual yield is less than the theoretical yield then the percent yield is less than 100%.Reason of this condition arising is the incompletion of reaction or loss of sample during recovery process.
In cases where percent yield is over 100% it indicates that more sample is recovered than the predicted amount.
For the given reaction, theoretical yield is calculated as,
128.132 g of sulfur dioxide gives 160.12 g of sulfur trioxide
∴705 g of sulfur dioxide gives 705×160.12/128.132= 881 g
Percent yield is, 586/881×100=66.51%
Therefore, the percent yield for the chemical reaction is 66.51%.
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The heat capacity of nickel is 0.444 J/(g · °C). Calculate the amount of heat needed to raise the temperature of 12 g of nickel from 23 °C to 69 °C. Now imagine those same joules were used instead to accelerate the same mass of nickel from rest. What would be the final speed, in m/s
Answer:245.088
Explanation: you subtract final temperature with initial temperature = 46 then multiply by grams = 552 then multiplied by J = 245.088
What is the ph of a peach with a [ –oh] = 3.2 × 10 –11 m?
A group of students is comparing the graphs of strong acid-strong base and weak acid-strong base titration curves, where the base is the titrant. Which statement inaccurately describes a difference between the two curves?
A. The initial pH for the weak acid-strong base curve is higher than the initial pH for the strong acid-strong base curve.
B. At the equivalence points, the pH of the weak acid-strong base is greater than the pH of the strong acid-strong base.
C. At the half-equivalence points, the pH of the weak acid-strong base is greater than the pH of the strong acid- strong base.
D. The steep-rise interval in the weak acid-strong base curve is more pronounced than in the strong acid-strong base curve.
The initial pH for the weak acid-strong base curve is higher than the initial pH for the strong acid-strong base curve. Hence, option A is correct.
What is a weak acid?Weak acids are acids that don't completely dissociate in solution.
A weak acid is an acetic acid. It has a of 1.8⋅[tex]10^{-5}[/tex]. Calculate how much it will dissociate in water. Since acetic acid is a weak acid so large part will not dissociate completely.
[tex]k_a=\frac{[CH_3COO^-]H^+]}{[CH_3COOH]}[/tex]
B is not true, it shows the titration curve for weak/strong acid titrated with a strong base. When choosing an indicator for colourimetric titration select one so that the pH jump at the equivalence point contains the interval p±1. Phenolphthalein has a p≈9, so to decide if it is a suitable indicator check if the pH jumps from 8 to 10 at the equivalence point.
C is not true either because of the very slow reaction.
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Determine the trends in radii for the following ions and atoms: Mg2+, F- , Ne, and Na+ .explain your choice
The trend for the radii is Mg²⁺ < Na+ < Ne <F⁻
What does Ionic size varies with number of protons ?With the increase in number of protons in the nucleus the electrons are more attracted towards nucleus and so the ionic radius decreases.
Ionic size increases with the addition of electrons and ionic size decreases with the loss of electrons.
Higher is the atomic number, higher will be the effective nuclear charge, lower will be the size.
F⁻
no. of proton=9
no of electron = 10
Na+
no. of proton=11
no of electron=10
Mg²⁺
no. of proton=12
no of electron=10
Ne
no. of proton=10
no of electron=10
Mg²⁺ < Na+ < Ne <F⁻
Therefore the trend for the radii is Mg²⁺ < Na+ < Ne <F⁻
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Hazmat Poison gas is in what class?
HAZMAT Class 6 Toxic and infectious substances.
Answer:
CLASS 2 Gases
Explanation:
Hope this helps
How many moles of N are in
0.227g N₂0?
Answer:
0.217 ×2. =9.86×10moles
44
If a utility burned 7.57 million tons of coal that was 2.00% sulfur by weight, how many tons of sulfur dioxide were emitted? Answer in scientific notation.
So mass of sulphur
[tex]\\ \rm\Rrightarrow 0.02\times 757\times 10^{6}[/tex]
[tex]\\ \rm\Rrightarrow 1514\times 10^4[/tex]
S+O_2–≥SO_2Moles =64/32=2
So
So tons of sulphur dioxide
[tex]\\ \rm\Rrightarrow 2(1516)10^4[/tex]
[tex]\\ \rm\Rrightarrow 3032\times 10^4ton[/tex]
Explanation:
2% of 2million tons of sulphur=
2÷100×7.57E9
That is;
[tex] \frac{2}{100} \times 7.57 \times 10 {}^{6} = 0.02 \times 7.57 \times 10 {}^{6} \\ = 2 \times 10 {}^{ - 2} \times7.57 \times 10 {}^{6} = 2 \times 7.57(10 {}^{ - 2 + 6}) \\ = 15.14 \times 10 {}^{4} (for \: sulphur) \\ for \: sulphur \: dioxide = so2 \\ the \: molar \: mass \: of \: so2 = 64g.mol {}^{ -1} \\ if \: 32grams \: of \: sulphur \: weighs \: 15.14 \times 10 {}^{4} tones \\ 64grams \: will \: weigh \: \frac{64}{32} \times 15.14 \times 10 {}^{4} \\ = 2 \times 15.14 \times 10 {}^{4} \\ = 30.28 \times 10 {}^{4} \\ or = 3.028 \times 10 {}^{5} tones[/tex]
Question 3
What part of a water molecule is the negatively charged side?
Answer:
The oxygen atom in water has a negative charge.
Definitions:Polar molecule: A molecule in which the centroid of the positive charges is different from the centroid of the negative charges.
Oxygen: A colorless, odorless, gaseous element constituting about one-fifth of the volume of the atmosphere and present in a combined state in nature. It is the supporter of combustion in air and was the standard of atomic, combining, and molecular weights until 1961, when carbon 12 became the new standard. Symbol: O; atomic weight: 15.9994; atomic number: 8; density: 1.4290 g/l at 0°C and 760mm pressure.
Water: A transparent, odorless, tasteless liquid, a compound of hydrogen and oxygen, H2O, freezing at 32°F or 0°C and boiling at 212°F or 100°C. that in more or less impure state constitutes rain, oceans, lakes, rivers, etc.: it contains 11.188 percent hydrogen and 88.812 percent oxygen, by weight.
Hydrogen: A colorless, odorless, flammable gas that combines chemically with oxygen to form water: the lightest of the known element. Symbol: H; atomic weight: 1.00797; atomic number: 1; density: 0.0899 g/l at 0°C and 760 mm pressure.
Atom: Am atom is the smallest constituent particle of a chemical element which has the properties of that element. They re comprised of at least an electron and a portion, as is the case for Hydrogen. Atoms of all other elements however, contain at least one neutron.
Proton: A positively charged elementary particle that is a fundamental constituent of all atomic nuclei. It is the lightest and most stable baryon, having a charge equal in magnitude to that of the electron, a spin of 1/2, and a mass of 1.673 × 10-27kg. Symbol: P.
Electron: An elementary particle that is a fundamental constituent of matter, having a negative charge of 1.602 × 10-19 coulombs, ha mass of 9.108 × 10-31 kilograms, and spin of 1/23, and existing independently or as the component outside the nucleus of an atom.
Neutron: An elementary particle having no charge, mass slightly greater than that of a proton, and spin of 1/2: a constituent of the nuclei of all atoms except those of hydrogen. Symbol: n.
What is a negative charge?A object has a negative charge when it consists of more electrons than protons.
With a partial positive charge on 2 Hs and a partial negative charge on oxygen, water molecules are polar molecules.
Actually, two hydrogen atoms and the core oxygen atom of water are covalently connected. Due to its greater electronegative nature than hydrogen, oxygen pulls the bound electron pair in the middle of the atom toward it.
When illustrating higher electron densities over oxygen, partial negative charge is used, whereas partial positive charge is used to illustrate lower densities over hydrogen atoms.
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A. What is the theoretical yield in grams for this reaction under the given conditions?
B. What is the percent yield for this reaction under the given conditions?
The theoretical yield of NH3 is 10.03 g while the percentage yield of NH3 is 22%.
What is the theoretical yield?The theoretical yield is defined as the yield of the product as obtained from the stoichiometry of the reaction.
Given that the reaction equation is; N2 + 3H2 ------> 2NH3
Number of moles of N2 = 9.80 g/28 g/mol = 0.35 moles
Number of moles of H2 = 1.77 g/ 2 g/mol = 0.885 moles
If 1 mole of N2 reacts with 3 moles of H2
0.35 moles reacts with 0.35 moles * 3 moles / 1 mole
= 1.75 moles
Hydrogen is the limiting reactant
Thus;
3 moles of H2 yields 2 moles of NH3
0.885 moles yields 0.885 moles * 2 moles/3 moles
= 0.59 moles
Theoretical yield of NH3 = 0.59 moles * 17 g/mol = 10.03 g
Percent yield = 2.21/10.03 * 100/1
= 22%
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What is the best definition of the enthalpy of vaporization, ^ Hvap?
A. The change in the disorder of a system when a liquid changes to a
gas
B. The change in the disorder of a system when a molecule forms
from its atoms
C. The energy needed to raise the temperature of a liquid to the
boiling point
D. The energy needed to change a liquid into a gas
Answer: D. The energy needed to change a liquid into a gas
Which of these reactions are acid-base reactions?
Answer:
The fifth answer choice (NH3 + H2O = NH4+ + OH-)
Explanation:
An acid-base reaction occurs when an acid and base combine, and the acid, (which is H2O in this case) "donates" a proton, or an H+ to the base. In this reaction, H2O gave one of its H+ to NH3, to make NH4+ and OH-. NH4+ now has a positive charge because it gained a positive ion, while OH- now has a negative charge because it gained a negative ion.
just need help with one question pls
Answer:
A large absorption at 2950 cm⁻¹ indicates that there is likely an sp³C-H functional group somewhere in the molecule. The "sp³" designation means that this is a single bond because these atoms have 4 orbitals available (s + p + p + p) for hybridizing, meaning only single bonds are possible.
When developing an experimental design, which action would improve the
quality of the results?
O A. Have a different researcher make the measurements.
OB. Ensure that it answers a question about cause and effect.
C. Include as many responding variables as possible.
OD. Keep the sample size of test subjects to a minimum.
SUBMIT
Answer:
A
Explanation:
I'm right I took the test
TUTOR Determining Molecular Weight
What is the molecular weight of Cr3(ASO4)2? amu
The molecular weight of Cr3(AsO4)2 is 433.827.
Is molecular weight the same As molar mass?Furthermore, the primary distinction between each is that molar mass gives the mass of a mole of a selected substance. While molecular weight is the mass of a molecule of a particular substance. At an equal time as the definition and devices are splendid for molar mass and molecular weight, the value is the same.
The sum of the atomic hundreds of all atoms in a molecule is based totally on a scale wherein the atomic loads of hydrogen, carbon, nitrogen, and oxygen are 1, 12, 14, and 16, respectively.
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pls this this solutions
number 3 pls and thank u
The statement which is not true is as follows:
The repulsive force between electrons on different atoms does not matter at all.Thus, the correct option is C.
What is Equilibrium?An equilibrium may be defined as the condition in which both the reactants and products are present in concentrations that have no additional propensity to alter with time so that there is no noticeable transformation in the possessions of the system.
The causation of repulsive force was thought to be made by the overlap of atomic orbitals and in between the electrons of diverse atoms, it matters a lot.
The equilibrium distance between nuclei of two covalently bonded atoms is called the bond length of that atom. It is the atomic separation at equilibrium.
Equilibrium occurs when the attractive and repulsive forces neglected the effect of each other in a specific state.
Therefore, it is well described above.
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For the following reaction, 22.0 grams of nitrogen monoxide are allowed to react with 5.80 grams of hydrogen gas . nitrogen monoxide ( g ) + hydrogen ( g ) nitrogen ( g ) + water ( l ) What is the maximum amount of nitrogen gas that can be formed? grams What is the FORMULA for the limiting reagent? What amount of the excess reagent remains after the reaction is complete? grams
NO is the limiting reagent and 4.34 g is the amount of the excess reagent that remains after the reaction is complete
What is a limiting reagent?The reactant that is entirely used up in a reaction is called as limiting reagent.
The reaction:
[tex]2NO(g) +2H_2(g)[/tex] → [tex]N_2 +2H_2O[/tex]
Moles of nitrogen monoxide
Molecular weight: [tex]M_(_N_O_)[/tex]=30g/mol
[tex]n_(_N_O_) =\frac{mass}{molar \;mass}[/tex]
[tex]n_(_N_O_) =\frac{22.0}{30g/mol}[/tex]
[tex]n_(_N_O_) = 0.73 mol[/tex]
Moles of hydrogen
Molecular weight: [tex]M_(_H_2_)[/tex]=30g/mol
[tex]n_(_H_2_) =\frac{mass}{molar \;mass}[/tex]
[tex]n_(_H_2_) =\frac{5.80g}{2g/mol}[/tex]
[tex]n_(_H_2_) = 2.9 mol[/tex]
Hydrogen gas is in excess.
NO is the limiting reagent.
The amount of the excess reagent remains after the reaction is complete.
[tex]n_(_N_2_) =[/tex] (2.9 mol- 0.73 mol NO x [tex]\frac{1 \;mol \;of \;H_2}{2 \;mole \;of \;NO}[/tex]) x [tex]\frac{2g \;of \;H_2}{mole \;of \;H_2}[/tex]
[tex]n_(_N_2_) =[/tex]4.34 g
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