Answer:
The correct answer is Option c (0.163 g).
Explanation:
Given:
Heat energy,
Q = 0.21 J
Specific heat,
c = 4.184 J/g°c
Change in temperature,
ΔT = 0.308°C
As we know,
⇒ [tex]Q=mc \Delta T[/tex]
By substituting the values, we get
[tex]0.21=m\times 4.184\times 0.308[/tex]
[tex]m=\frac{0.21}{0.308\times 4.184}[/tex]
[tex]=\frac{0.21}{1.28867}[/tex]
[tex]=0.163 \ g[/tex]
A chemist measures the amount of iodine solid produced during an experiment. He finds that of iodine solid is produced. Calculate the number of moles of iodine solid produced. Round your answer to significant digits.
The question is incomplete, the complete question is:
A chemist measures the amount of iodine solid produced during an experiment. He finds that 8.31 g of iodine solid is produced. Calculate the number of moles of iodine solid produced. Round your answer to the correct number of significant digits.
Answer: The number of moles of solid iodine produced is 0.0327 moles
Explanation:
The number of moles is defined as the ratio of the mass of a substance to its molar mass. The equation used is:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] ......(1)
Given mass of solid iodine = 8.31 g
Molar mass of solid iodine = 253.8089 g/mol
Plugging values in equation 1:
[tex]\text{Moles of solid iodine}=\frac{8.31g}{253.8089g/mol}=0.0327mol[/tex]
Hence, the number of moles of solid iodine produced is 0.0327 moles
Qual número atômico do ferro?
Answer:
The answer is Iron.
Explanation:
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Draw 2,3-dichloro octane
Answer:
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Identify a process that is NOT reversible. Identify a process that is NOT reversible. melting of snow baking of bread deposition of carbon dioxide freezing water melting of aluminum
Answer:
Identify a process that is NOT reversible.
Melting of snow
baking of bread
deposition of carbon dioxide
freezing water
melting of aluminum
Explanation:
A physical change is the one in which there is a change only in its physical state, color, the appearance of the substance. But the chemical composition of the substance remains unchanged.
It is a temporary change and can be reversed easily.
For example:
melting, freezing, deposition etc.
Baking is a permanent change and the chemical composition of the substance changes.
Hence, among the given options, baking of bread is not a reversible change.
Out of the following all are physical changes except baking of bread and physical changes are reversible so the process which is not reversible is baking of bread.
What are physical changes?Physical changes are defined as changes which affect only the form of a substance but not it's chemical composition. They are used to separate mixtures in to chemical components but cannot be used to separate compounds to simpler compounds.
Physical changes are always reversible using physical means and involve a change in the physical properties.Examples of physical changes include melting,boiling , change in texture, size,color,volume and density.Magnetism, crystallization, formation of alloys are all reversible and hence physical changes.
They involve only rearrangement of atoms and are often characterized to be changes which are reversible.
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A chemist combines 33 g of methane with 289 g of oxygen to from 189 g of carbon dioxide and 30 g of water. Determine if the results of the following word problem adheres to the Law of Conservation of Mass.
Answer:
The correct answer is - no not adhere to the law of mass conservation.
Explanation:
According to the law of mass conservation in an isolated system, the mass can not be created or destroyed and in a chemical or physical change, the mass of products should be always equal to the mass of reactants.
On the basis of the law the mass of the chemical reaction-
Mass of products = mass of reactants
33 g of methane + 289g of oxygen = 189g of carbon dioxide + 30g of water
322g ≠ 219 g
which means this reaction does not adhere to the law of conservation.
define saturated and unsaturated fats
Saturated fatty acids lack double bonds between the individual carbon atoms, while in unsaturated fatty acids there is at least one double bond in the fatty acid chain. Saturated fats tend to be solid at room temperature and from animal sources, while unsaturated fats are usually liquid and from plant sources.
Answer:
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A product of homolytic fission can never be
a - charged
b - nucleophile
c- both
d-none of these
Answer:
both
Explanation:
A homolytic fission is said to have occurred when the breakage of a bond between two atoms leaves each of the bonding atoms with equal number of electrons. Homolytic fission often results in the creation of radicals.
Since homolytic fission yields two species with equal number of electrons(usually odd number of electrons), the products of such process can not be charged. They can not be nucleophiles because nucleophiles need to possess two electrons which can be shared with another chemical specie.
The length of a covalent bond depends upon the size of the atoms and the bond order.
a. True
b. False
Answer:
True
Explanation:
The length of covalent bond depends upon the size of atoms and the bond order.
The angular momentum quantum number (l) value of 0 indicates the ________ subshell.
Answer:
indicates the number of subshells
How to calculate the actual volume (ml) of water removed from the burette with water
density 1 g/ml:
i. 5mL of water removed
Answer:
Explanation:
The density of pure water is 1 gram per 1 milliliter or one cubic cm. By knowing the density of water we can use it in dilution equations or to calculate the specific gravity of other solutions.
It can also help us determine what other substances are made of using the water displacement experiment. This is done by observing how much water is displaced when an object is submerged in the water. As long as you know the density of the water, the mass of the object being submerged and the volume of increase you can calculate the density of the object.
This was done by the great Archimedes in discovering what composed the kings crown.
Which diagram correctly depicts the trend in electronegativity?
a.
b.
c.
d.
The electronegativity increases across the period and decreases down the group. Thus, option B is correct.
Electronegativity can be defined as the tendency of an atom to gain or attract an electron. The electronegativity has been dependent on the size of the atom, as well as the atomic number and valence electrons.
The atom with the requirement of a less number of atoms to complete its octet can easily gain the electron and thereby have high electronegativity. The atomic size also plays a role in the electronegativity of the atom.
The atom with a bigger size has the lesser force of attraction from the nucleus and thus has difficulty attracting the electron, however, the smaller size atom can easily attract the electron with the attraction force from the nucleus.
Thus, the elements with smaller sizes and a high number of valence electrons are more electronegative. In the periodic table, on moving from left to right the valence electrons increase, thus the electronegativity increases.
On moving down the group, the element size increase, thus the electronegativity decreases down the group.
The electronegativity increases across the period and decreases down the group. Thus, option B is correct.
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Draw the skeletal structure for: (E)-hept-5-en-2-one
Answer:
Draw the skeletal structure for: (E)-hept-5-en-2-one
Explanation:
The root word hept indicates that the given compound has seven carons in its longest chain.
-en- primary suffix indicates that the compound has one double bond in it.
2-one indicates that the compound has -C=O bond in the second carbon.
The prefix (E) indicates that the highest priority groups are on the opposite direction of the double bond.
The structure of the given molecule is:
Suppose a 0.042M aqueous solution of phosphoric acid (H3PO4) is prepared. Calculate the equilibrium molarity of HPO4^−2.
Answer:
2.89x10⁻⁵M = [HPO₄²⁻]
Explanation:
The equilibrium of H3PO4 in water occurs H2PO4-:
H3PO4(aq) + H2O(l) ⇄ H3O⁺(aq) + H2PO4⁻(aq)
pKa = 2.16. And as pKa = -log Ka; Ka = 10^-2.16
Ka = 6.9183x10⁻³ = [H3O⁺] [H2PO4⁻] / [H3PO4]
As both [H3O⁺] and [H2PO4⁻] comes from the same equilibrium,
[H3O⁺]=[H2PO4⁻] :
[H3O⁺] = X
[H2PO4⁻] = X
[H3PO4] = 0.042 - X
Where X is reaction coordinate
Replacing:
6.9183x10⁻³ = [X] [X] / [0.042 - X]
6.9183x10⁻³ = X² / 0.042 - X
2.905686x10⁻⁴ - 6.9183x10⁻³X - X² = 0
Solving for X:
X = -0.02M. False solution. There is no negative concentration.
X = 0.014M. Right solution
[H2PO4⁻] = 0.014M
In the second equilibrium:
H2PO4⁻(aq) + H2O(l) ⇄ HPO4-(aq) + H3O+(aq)
Based on the same principles of the last equilibrium:
pKa2 = 7.21
Ka2 = 6.166x10⁻⁸ = [HPO4-] [H3O+] / [H2PO4⁻]
[HPO4-] = X
[H3O+] = X
[H2PO4⁻] = 0.014M - X
6.166x10⁻⁸ = X² / [0.014M - X]
8.3623x10⁻¹⁰ - 6.166x10⁻⁸X - X² = 0
Solving for X:
X = -0.0000289485. False solution.
X =
2.89x10⁻⁵M = [HPO₄²⁻]All light waves can be described in terms of their speed, frequency, and___
Answer:
all light waves can be described in terms of their speed, frequency and wavelength
Explanation:
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A chemist measures the energy change
ΔH during the following reaction:
2NH3(g)→N2(g)+3H2(g)
ΔH=160kJUse the information to answer the following questions.This reaction is:__________.
a. endothermic
b. exothermic
Suppose 70.9 g of NH3 react. Will any heat be released or absorbed?
a. Yes, absorbed
b. Yes, released
c. No.
If you said heat will be released or absorbed in the second part of this question, calculate how much heat will be released or absorbed. Round your answer to 3 significant digits.
Answer:
For (1): The correct option is (a)
For (2): The correct option is (a) and 333.6 kJ of heat will be absorbed when 70.9 g of ammonia reacts.
Explanation:
There are 2 types of reactions that are classified based on enthalpy change:
Endothermic reactions: These are the reactions where heat is absorbed by the reaction. The change in enthalpy of the reaction, [tex]\Delta H_{rxn}[/tex] is positive for these reactions.
Exothermic reactions: These are the reactions where heat is released by the reaction. The change in enthalpy of the reaction, [tex]\Delta H_{rxn}[/tex] is negative for these reactions.
For (1):For the given chemical reaction:
[tex]2NH_3(g)\rightarrow N_2(g)+3H_2(g);Delta H=160kJ[/tex]
As the change in enthalpy or heat of the reaction is positive. Thus, the reaction is an endothermic reaction because heat is absorbed by the reaction.
For (2):When ammonia reacts, some amount of heat will be absorbed by the reaction. Thus, we can say the heat will be absorbed.
The number of moles is calculated by using the equation:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] ......(1)
Given mass of ammonia = 70.9 g
Molar mass of ammonia = 17 g/mol
Using equation 1:
[tex]\text{Moles of ammonia}=\frac{70.9g}{17g/mol}=4.17mol[/tex]
By stoichiometry of the reaction:
If 2 mole of ammonia reacts, the heat absorbed is 160 kJ
So, if 4.17 moles of ammonia reacts, the heat absorbed will be = [tex]\frac{160kJ}{2mol}\times 4.17mol=333.6kJ[/tex]
Hence, 333.6 kJ of heat will be absorbed when 70.9 g of ammonia reacts
g in the following three compounds(1,2,3) arrange their relative reactivity towards the reagent CH3Cl / AlCl3. Justify your order
Answer:
3 > 2> 1
Explanation:
Aromatic compounds undergo electrophilic substitution reaction with several electrophiles.
Some substituted benzenes are more reactive towards electrophilic aromatic substitution than unsubstituted benzene.
Certain groups of substituents increase the ease with which an aromatic compound undergoes aromatic substitution.
If we look at the compounds closely, we will notice that only toluene leads to easy reaction with CH3Cl / AlCl3. Thus is due to the +I inductive effect of -CH3 which stabilizes the negatively charged intermediate produced in the reaction.
What is the formula of the compound Pentasilicon trioxide ?
Answer: the molecular formula of trioxide is ClOClO3 or Cl2O4
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1. Show that heat flows spontaneously from high temperature to low temperature in any isolated system (hint: use entropy change that occurs during the process for your proof).
2. Work out the entropy change for the decomposition of mercuric oxide using mathematical and graphical arguments.
Answer:
1 ) Δs ( entropy change for hot block ) = - Q / th ( -ve shows heat lost to cold block )
Δs ( entropy change for cold block ) = Q / tc
∴ Total Δs = ΔSc + ΔSh
= Q/tc - Q/th
2) ΔSdecomposition = Δh / Temp = ( 181.6 * 10^3 / 773 ) = 234.928 J/k
Explanation:
1) To show that heat flows spontaneously from high temperature to low temperature
example :
Pick two(2) solid metal blocks with varying temperatures ( i.e. one solid block is hot and the other solid block is cold )
Place both blocks for time (t ) in an insulated system to reduce heat loss or gain to or from the environment
Check the temperature of both blocks after time ( t ) it will be observed that both blocks will have same temperature after time t ( first law of thermodynamics )
Δs ( entropy change for hot block ) = - Q / th ( -ve shows heat lost to cold block )
Δs ( entropy change for cold block ) = Q / tc
∴ Total Δs = ΔSc + ΔSh
= Q/tc - Q/th
2) Entropy change for Decomposition of mercuric oxide
2HgO (s) → 2Hg(l) + O₂ (g)
Δs = positive
there is transition from solid to liquid and the melting point of mercury ( the point at which reaction will take place ) = 500⁰C
hence ΔSdecomposition = S⁻ Hg - S⁻ HgO =
Δh of reaction = 181.6 KJ
Temp = 500 + 273 = 773 k
hence ΔSdecomposition = Δh / Temp = ( 181.6 * 10^3 / 773 ) = 234.928 J/k
What is the volume of a flask containing 0.199mol of Cl2at a temperature of 313K and a pressure of 1.19atm
Answer:
43.0 L
Explanation:
Step 1: Given and required data
Moles of chlorine gas (n): 0.199 molTemperature (T): 313 KPressure (P): 1.19 atmIdeal gas constant (R): 0.0821 atm.L/mol.KStep 2: Calculate the volume of the flask (V)
We will use the ideal gas equation.
P × V = n × R × T
V = n × R × T / P
V = 1.99 mol × (0.0821 atm.L/mol.K) × 313 K / 1.19 atm = 43.0 L
The answer is 4.30 L
What is oxygen's half-equation?
answer; 1/ 20_2[2-] +2e - ->0.
How many liters of hydrogen can be produced at a pressure of 2 atm and a temperature of 298 K
Answer:
1.17 L of H₂
Explanation:
We'll begin by calculating the number of mole in 2.3 g of Mg. This can be obtained as follow:
Mass of Mg = 2.3 g
Molar mass of Mg = 24 g/mol
Mole of Mg =?
Mole = mass /molar mass
Mole of Mg = 2.3 / 24
Mole of Mg = 0.096 mole
Next, we shall determine the number of mole of H₂ produced by the reaction of 2.3 g (i.e 0.096 mole) of Mg. This can be obtained as follow:
Mg + 2HCl —> MgCl₂ + H₂
From the balanced equation above,
1 mole of Mg reacted to 1 mole of H₂.
Therefore, 0.096 mole of Mg will also react to produce 0.096 mole of H₂.
Finally, we shall determine volume of H₂ produced from the reaction. This can be obtained as follow:
Number of mole (n) of H₂ = 0.096 mole
Pressure (P) = 2 atm
Temperature (T) = 298 K
Gas constant (R) = 0.0821 atm.L/Kmol
Volume (V) of H₂ =?
PV = nRT
2 × V = 0.096 × 0.0821 × 298
Divide both side by 2
V = (0.096 × 0.0821 × 298) /2
V = 1.17 L
Therefore, 1.17 L of H₂ were obtained from the reaction.
Which of the following statements correctly explains why bromination reactions are more selective than chlorination reactions.
a. bromine radical is less stable than chlorine radical, so it is more reactive and less choosy
b. bromine radical is more stable than chlorine radical, so it is more reactive and less choosy
c. bromine radical is more stable than chlorine radical, so it is less reactive and more choosy
d. bromine radical is less stable than chlorine radical, so it is less reactive and more choosy
e. relative radical stability is 3' radicals > 2" radicals> 1 radicals when bromine radicals snatch hydrogens from alkanes, but when chlorine radicals snatch hydrogens the resulting alkyl radical stability is 3 radicals < 2 radicals< 1' radicals
Answer: A bromine radical is more stable than chlorine radical, so it is less reactive and more choosy.
Explanation:
A chlorine atom being more electronegative in nature is able to attract a hydrogen atom more readily towards itself as compared to a bromine atom.
Since bromine is less electronegative in nature so bromine will be more selective as a hydrogen abstracting agent. As a result, bromine radical is more stable in nature than chlorine radical.
Thus, we can conclude that bromine radical is more stable than chlorine radical, so it is less reactive and more choosy.
g 250. mL of a solution is created and has a molarity of 1.50 M. What is the molality of this solution if the volume and density of the pure solvent is about the same as the volume and density of the final solution and the density of the pure solvent is 1.15 g/mL
Answer:
1.30 m
Explanation:
First we calculate the number of moles of solute in the solution, using the definition of molarity:
Molarity = moles / litersConverting 250 mL ⇒ 250 / 1000 = 0.250 Lmoles = 1.50 M * 0.250 L = 0.375 molesThen we calculate the mass of solvent, using the given volume and density:
1.15 g/mL * 250 mL = 287.5 gConverting 287.5 g to kg ⇒ 287.5 / 1000 = 0.2875 kgNow we calculate the molality of the solution:
molality = moles of solute / kg of solvent = 0.375 mol / 0.2875 kgmolality = 1.30 mg Consider two different liquids at atmospheric pressure: hexane and water. Hexane has a higher vapor pressure than water. As a result, the temperature at which hexane will boil will be [ Select ] water and its vapor pressure when it is boiling will be [ Select ] water when water is boiling.
Answer:
Lower than
Higher than
Explanation:
The vapour pressure and boiling point of liquids are inversely related. Thus, the higher the vapour pressure of a liquid, the lower it's boiling point. Lower vapour pressure implies that the liquid is easily converted into vapour phase.
If hexane has a higher vapour pressure than water then its boiling point is lower than that of water and its vapor pressure when it is boiling will be higher than water when water is boiling.
what is the qualitative analysis of (nh4) 2co3 using NaOH, HCL, BaCL2, and AgNO3
Answer:
qualatatiev is fs-hj_jakakak
An ionic compound contains an unknown ion X and has the formula X3N2. Ion X contains 10 electrons. Write down the chemical symbol of X?
Answer:
Mg3N2
Explanation:
it would be magnesium as it would loss to electron so it would have 10 electron. you can see in the picture above .
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Calculate the number of ATOMS in 1.0 mole of O2. blank x 1024
Answer:
6.023*10^23........ .......
When taking a measurement with a pH meter, keep the instrument in the _______storage solution or water until it is needed. Rinse the pH meter with
_______deionized water or acetone and gently pat dry. Place the meter in the sample solution, and record the measurement when the pH _______stabilizes or reaches the maximum value
Answer:
storage solution , deionized water, stabilizes
Explanation:
A pH meter is a scientific device or instrument that is used to measure the pH of a given aqueous solution thereby determining the nature of the solution whether it is acidic or basic or neutral.
While using the pH meter or taking the measurement using the pH meter --
it should be kept in a storage solution for effective working.Before using the device, it is rinsed with a deionized water and pat dry.Record the measurements when the pH meter stabilizes.PLEASE HELP!!!!
Which of the following lists describes characteristics of an acid? (3 points)
Bitter taste, high pH, and caustic
Sour taste, low pH, and dissolves metals
Sour taste, high pH, and dissolves metals
Slippery, low pH, and caustic
Acids have sour taste, low pH and dissolves metals.
The list that describes the characteristics of an acid is that it has sour taste, low pH, and dissolves metals.
Characteristics of an acidAn acid is a chemical substance that has the ability to donate hydrogen ions when involved in a chemical reaction.
The following are the characteristics or features of an acid:
They have a sour taste when tasted.When measured using a pH scale it is less than 7(low pH).They react with active metals to yield hydrogen gas.Therefore, the list that describes the characteristics of an acid is that it has sour taste, low pH, and dissolves metals.
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What is the cell potential of an electrochemical cell that has the half-reactions shown below?
Ag⁺ + e⁻ → Ag
Fe → Fe³⁺ + 3e⁻
Answer:
E°(Ag⁺/Fe°) = 0.836 volt
Explanation:
3Ag⁺ + 3e⁻ => Ag°; E° = +0.800 volt
Fe° => Fe⁺³ + 3e⁻ ; E° = -0.036 volt
_________________________________
Fe°(s) + 3Ag⁺(aq) => Fe⁺³(aq) + 3Ag°(s) ...
E°(Ag⁺/Fe°) = E°(Ag⁺) - E°(Fe°) = 0.800v - ( -0.036v) = 0.836 volt
