Explanation:
The standard entropy change of a reaction has a positive value. This reaction results in an increase in entropy.
Positive entropy means the system has increased its degree of disorderness.
Caffeine is a bitter stimulant drug and is found in varying quantities in seeds, leaves, and so on.
a. True
b. False
Answer:
The answer Is B.....False
Choose all the answers that apply. Silicon (Si) has 14 protons and an atomic mass of 28. Silicon has _____. three electron shells 14 electrons 14 neutrons two electron shells 28 electrons
Answer:
three electron shells
14 electrons
14 neutrons
Explanation:
Silicon has three electron shells arranged as follows; 2, 8, 4. This corresponds to the fact that silicon is a member of group 14 of the periodic table.
Note that, the number of protons in an atom is the same as the number of electrons in the neutral atom. Since Silicon has 14 protons, it also has 14 electrons likewise.
The mass number of silicon is 28 but number of neutrons= mass number - number of protons. Since mass number = 28, then there are 14 neutrons in silicon.
Explain how the existence of isotopes relates to the number of neutrons within the nuclei of an element.
Answer:
because of it less attraction and its neutral position
Answer:
The existence of isotopes relates to the number of neutrons within the nuclei of an element because isotopes contain the same amount of protons (based on what element they are) but different number of neutrons in their nuclei. Because they have a different amount of neutrons, than the original element
,they also have a different atomic mass.
Explanation:
hope it helps!
The diagram above shows the hydrides of groups 14, 15, 16, and 17 elements. Why does H20, HF, and NH3 have much higher boiling points than the rest of the molecules in their groups?
Answer:
Hydrogen Bonding
Explanation:
Hydrogen Bonding occurs when a hydrogen atom is bonded to N, O, and F atoms.
The molecules H₂O, HF, and NH₃ all experience hydrogen bonding, which is a relatively strong IMF, causing the molecules to have stronger attraction to each other. Having a stronger attraction between molecules results in more energy required to separate them, thus these molecules will have a higher boiling point than the rest of the molecules in their group.
Consider the reaction: CaCO3(s)CaO(s) CO2(g) Using standard absolute entropies at 298K, calculate the entropy change for the system when 1.58 moles of CaCO3(s) react at standard conditions.
Answer:
the entropy change for the system when 1.58 moles of CaCO3(s) react at standard conditions is 253.748 J/K
Explanation:
Given the data in the question;
CaCO₃(s) → CaO(s) + CO₂(g)
1.58 moles 1.58 moles 1.58 moles
Since 1 mole of CaCO₃ gives 1 mole of CaO and 1 mole of CO₂
Thus, 1.58 mole of CaCO₃ gives 1.58 moles of CaO and 1.58 moles of CO₂.
Now,
At 298 K, standard entropy values are;
ΔS° ( CaCO₃ ) = 92.9 J/mol.K
ΔS° ( CaO ) = 39.8 J/mol.K
ΔS° ( CO₂ ) = 213.7 J/mol.K
So,
ΔS°[tex]_{system[/tex] = ∑ΔS°( product ) - ∑ΔS°( reactant )
ΔS°[tex]_{system[/tex] = [ ΔS°(CaO) + ΔS°( CO₂ ) ] - ΔS°( CaCO₃ )
we substitute
ΔS°[tex]_{system[/tex] = [ 39.8 J/mol.K + 213.7 J/mol.K ] - 92.9 J/mol.K
ΔS°[tex]_{system[/tex] = 160.6 J/mol.K
i.e, for 1 mol CaCO₃, ΔS°[tex]_{system[/tex] = 160.6 J/mol.K
Now, for 1.58 mol CaCO₃,
ΔS°[tex]_{system[/tex] = 1.58 mol × 160.6 J/mol.K
ΔS°[tex]_{system[/tex] = 253.748 J/K
Therefore, the entropy change for the system when 1.58 moles of CaCO3(s) react at standard conditions is 253.748 J/K
Determine the molecular formula of a compound if it is composed of 40.92% carbon, 4.58% hydrogen, and 54.50% oxygen. The molar mass is 176.12 g/mol.
A) C3H8O3.
B) CH2O.
C) C2H3O2.
D) C3H4O3.
Answer:
No correct answer listed. See explanation for defense.
Explanation:
Given
C: 40.92% => 40.92g/100wt => (40.92/12)moles C = 3.41 moles O
H: 4.58% => 4.58g/100wt => (4.58/1)moles H = 4.58 moles H
O: 54.50% => 54.5g/100wt => (54.5/16)moles O = 3.41 moles O
Empirical ratio => C : H: O => (3.41/3.41) : (4.58/3.41) : (3.41/3.41) => 1 : 1.34 : 1
=> C : H : O => 3(1 : 1.34 : 1) => 3 : 4 : 3 => Empirical Formula C₃H₄O₃
Molecular Weight = Empirical Formula Wt x N
176.12 = 88 x N
N = whole number multiple of empirical formula = 176.12/88 = 2
∴ Molecular Formula => (C₃H₄O₃)₂ => C₆H₈O₆
Note => Only ionic compounds (salts) have subscripts reduced to lowest whole number ratios. Molecular compounds as C₆H₈O₆ are not reduced to lowest whole number ratios. Therefore, there is no correct answer in the answer choice list for the 'Molecular Formula'. Doc :-)
Suppose we have two rock samples, A and B. Rock A was subject to both physical and chemical weathering while rock B was subject to chemical weathering only. Which rock would experience more chemical weathering? Why? (2pts) (Hint: consider the effect of surface area on the rate of chemical weathering)
Answer:
Rock A will have far more chemical weathering than Rock B due to the rise in area effect
Explanation:
Rock A undergoes both Physical and Chemical weathering. So, thanks to physical weathering there'll appear cracks within the rock, which can, in turn, increase the area of rock on which weathering is occurring. So, Chemical weathering will happen much faster now as there's a rise in the area. within the case of Rock B, there's only chemical weathering therefore the increase in the area won't be that very much like compared to Rock A.
Enzyme catalyzing breakdown of atp to adp
Answer:
ATP hydrolase
Explanation:
Enzymes are biological catalysts which perform diverse functions in the body. Enzymes are specific in their mode of action because an enzyme fits into its substrate as a key fits into a lock.
The particular enzyme that catalyzes the breakdown of ATP to ADP is ATP hydrolase. The phosphate released by the action of this enzyme is used in the phosphorylation of other compounds thereby making them more reactive.
Flag A solution of the weak acid, HF, and a solution of the strong acid, HCl, have the same pH. Which solution will require the most sodium hydroxide, NaOH, to neutralize
Answer:
C) Both will require the same amount because the concentrations are equal.
Explanation:
The pH of a solution is defined as:
pH = -log [H+]
This H+ is the ion that reacts with OH- (From NaOH) as follows:
H+ + OH- → H2O
When all H+ reacts, we can say the solution was neutralized.
Now, as both, the solution with the weak acid and the solution with strong acid have the same pH, we can say that their [H+] is the same. Assuming the volume of both solutions is the same:
Both will require the same amount because the concentrations are equal.
What is the oxidation state of nitrogen in N ?
Answer:
+5
Explanation:
What is the fourth quantum number of the 3p electron in aluminum,
1s^2 2s^2 2p^6 3s^2 3p^1?
A. ms = -1
B. ms = +1/2
C. ms=0
D. ms = +1
Explanation:
here's the answer to your question
The quantum numbers are defined as the set of four numbers with the help of which we can get complete information about the electrons in an atom. The fourth quantum number is the spin quantum number. Here ms for 3p electron in 'Al' is ms = + 1/2. The correct option is B.
The quantum number which describes the spin orientation of the electron is defined as the spin quantum number. Since the electron can spin only in two ways, clockwise and anti-clockwise, the spin quantum number can have either the value +1/2 or -1/2 depending upon the direction of spin.
Thus for 3p electron in 'Al' ,ms is option B.
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For the reaction of oxygen and nitrogen to form nitric oxide, consider the following thermodynamic data :
ΔH∘rxn 180.5kJ/mol
ΔS∘rxn 24.80J/(mol⋅K)
Required:
a. Calculate the temperature in kelvins above which this reaction is spontaneous
b. Calculate the equilibrium constant for the following reaction at room temperature, 25°C
Answer:
a. 7278 K
b. Kc = 4.542 × 10⁻³¹
Explanation:
a.
The reaction is spontaneous when ΔG° < 0. We can calculate ΔG° using the following expression.
ΔG° = ΔH° - T × ΔS°
Then, the reaction will be spontaneous when,
ΔH° - T × ΔS° < 0
T > ΔH°/ΔS
T > (180.5 × 10³ J/mol)/(24.80J/mol⋅K)
T > 7278 K
b.
First, we will calculate ΔG° at 25 °C (298 K)
ΔG° = ΔH° - T × ΔS°
ΔG° = (180.5 × 10³ J/mol) - 298 K × (24.80J/mol⋅K) = 1.731 × 10⁵ J/mol
Then, we will calculate the equilibrium constant (Kc) using the following expression.
ΔG° = - R × T × ln Kc
-ΔG°/R × T = ln Kc
-(1.731 × 10⁵ J/mol)/(8.314 J/mol.K) × 298 K = ln Kc
Kc = 4.542 × 10⁻³¹
In a first order reaction 40% of reactant gets converted into product in 30 minutes. What time would it require to convert 75% into product?
In a first order reaction 40% of reactant gets converted into product in 30 minutes. The time would it require to convert 75% into product is 81.57 minutes.
What is first order reaction?First order reaction is defined as a chemical reaction in which the concentration of just one ingredient directly affects the pace of the reaction. If the first-order reactant concentration is doubled in these reactions, the reaction rate will likewise double. Chemical reactions classified as first order kinetics have rates of reaction that depend on the molar concentration of one component.
First order reaction = 2.303 / t log a / (a-x)
k = 2.303 / 30 log 100 (100 - 40)
k = 0.0767 log 1.66
k = 0.017 min⁻¹
The time required to convert 75 % product
t = 2.303 / 0.017 log 100 (100 - 75)
t = 135.5 log 4
t = 135.5 x 0.602
t = 81.57 minutes
Thus, in a first order reaction 40% of reactant gets converted into product in 30 minutes. The time would it require to convert 75% into product is 81.57 minutes.
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A rigid, sealed container that can hold 26 L of gas is filled to a pressure of
5.97 atm at 374 °C. The pressure suddenly decreases to 3.64 atm. What is
the new temperature inside the container, in units of °C?
Answer:
121 °C
Explanation:
From the question given above, the following data were obtained:
Initial pressure (P₁) = 5.97 atm
Initial temperature (T₁) = 374 °C
Final pressure (P₂) = 3.64 atm
Final temperature (T₂) =?
NOTE: Volume = constant
Next, we shall convert 374 °C to Kelvin temperature. This can be obtained as follow:
T(K) = T(°C) + 273
Initial temperature (T₁) = 374 °C
Initial temperature (T₁) = 374 °C + 273
Initial temperature (T₁) = 647 K
Next, we shall determine the final temperature. This can be obtained as follow:
Initial pressure (P₁) = 5.97 atm
Initial temperature (T₁) = 647 K
Final pressure (P₂) = 3.64 atm
Final temperature (T₂) =?
P₁ / T₁ = P₂ / T₂
5.97 / 647 = 3.64 / T₂
Cross multiply
5.97 × T₂ = 647 × 3.64
5.97 × T₂ = 2355.08
Divide both side by 5.97
T₂ = 2355.08 / 5.97
T₂ = 394 K
Finally, we shall convert 394 K to celsius temperature. This can be obtained as follow:
T(°C) = T(K) – 273
Final temperature (T₂) = 394 K
Final temperature (T₂) = 394 – 273
Final temperature (T₂) = 121 °C
Thus, the new temperature is 121 °C
Write the separation scheme for the isolation of triphenylmethanol from the reaction mixture once the reaction is complete. The separation begins after the addition of HCl and water to the reaction and includes the column chromatography procedure to further purify crude triphenylmethanol isolated in the day 1 procedure.
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Write the cell notation for an electrochemical cell consisting of an anode where Mn (s) is oxidized to Mn2 (aq) and a cathode where Co2 (aq) is reduced to Co (s) . Assume all aqueous solutions have a concentration of 1 mol/L.
Answer:
Mn(s)/Mn^2+(aq)//Co^2+(aq)/Co(s)
Explanation:
In writing the cell notation for an electrochemical cell, the anode is written on the left hand side while the cathode is written on the right hand side. The two half cells are separated by two thick lines which represents the salt bridge.
For the cell discussed in the question; the Mn(s)/Mn^2+(aq) is the anode while the Co^2+(aq)/Co(s) half cell is the cathode.
Hence I can write; Mn(s)/Mn^2+(aq)//Co^2+(aq)/Co(s)
1. Why is it necessary to equalize the pressure(i.e, have the water level the same in each tube) before taking a volume reading?
2. Why is it important to use water that has been pre-saturated with CO2 in the gas burettes?
3.If your antacid sample had been contaminated by moisture, what effect(if any )would you expect this to have on your result
4.Explain why an'antacid is called as such,what is the role of the NAHCO3 or CACO3 in reactions?
Answer:
If you contact water with a gas at a certain temperature and (partial) pressure, the concentration of the gas in the water will reach an equilibrium ('saturation') according to Henry's law.
Explanation:
This means: if you increase the pressure (e.g. by keeping the vial closed), the CO2 concentration will increase. So it simply depends what concentration you need for your assay: 'CO2-saturated' water at low pressure or 'CO2-saturated' water at high pressure.
A researcher is attempting to produce ethanol using an enzyme catalyzed batch reactor. The ethanol is produced from corn starch by first-order kinetics with a rate constant of 0.05 hr-1. Assuming the concentration of ethanol initially is 1 mg/L, what will be the concentration of ethanol (in mg/L) after 24 hours
Answer:
The correct solution is "3.32 gm/L".
Explanation:
Given:
Rate constant,
[tex]K = 0.05 \ hr^{-1}[/tex]
Time,
[tex]t = 24 \ hours[/tex]
Concentration of ethanol,
[tex]C_o= 1 \ mg/L[/tex]
Now,
The concentration of ethanol after 24 hours will be:
⇒ [tex]C_o=C\times e^{-K\times t}[/tex]
By putting the values, we get
[tex]1=C\times e^{-0.05\times 24}[/tex]
[tex]1=C\times 0.30119[/tex]
[tex]C= 3.32 \ gm/L[/tex]
5. How many grams of tin metal can be produced from smelting (heating) of a 4.5 kilograms of tin (IV) oxide? (Note: Elemental tin and oxygen gas are the only products of this reaction).
Answer:
About 3500 grams of tin.
Explanation:
We want to determine amount of tin metal (in grams) that can be produced from smelting 4.5 kilograms of tin(IV) oxide.
First, write the chemical compound. Since our cation is tin(IV), it forms a 3+ charge. Oxygen has a 2- charge, so we will have two oxygen atoms. Hence, tin(IV) oxide is given by SnO₂.
By smelting it, we acquire elemental tin and oxygen gas. Hence:
[tex]\text{SnO$_2$}\rightarrow \text{Sn} + \text{O$_2$}[/tex]
(Note: oxygen is a diatomic element.)
The equation is balanced as well.
To convert from SnO₂ to only Sn, we can first convert from grams of SnO₂ to moles, use mole ratios to convert to moles of Sn, and then from there convert to grams.
Since Sn has a molar mass of 118.71 g/mol and oxygen has a molar mass of 15.999 g/mol, the molar mass of SnO₂ is:
[tex](118.71)+2(15.999) = 150.708\text{ g/mol}[/tex]
Therefore, given 4.5 kilograms of SnO₂, we can first convert this into grams using 1000 g / kg and then using the ratio:
[tex]\displaystyle \frac{1\text{ mol SnO$_2$}}{150.708\text{ g SnO$_2$}}[/tex]
We can convert this into moles.
Next, from the chemical equation, we can see that one mole of SnO₂ produces exactly one mole of Sn (and also one mole of O₂). So, our mole ratio is:
[tex]\displaystyle \frac{1\text{ mol Sn}}{1\text{ mol SnO$_2$}}[/tex]
With SnO₂ in the denominator to simplify units.
Finally, we can convert from moles Sn to grams Sn using its molar mass:
[tex]\displaystyle \frac{118.71\text{ g Sn}}{1\text{ mol Sn}}[/tex]
With the initial value and above ratios, we acquire:
[tex]\displaystyle 4.5\text{ kg SnO$_2$}\cdot \frac{1000 \text{ g SnO$_2$}}{1\text{ kg SnO$_2$}}\cdot \displaystyle \frac{1\text{ mol SnO$_2$}}{150.708\text{ g SnO$_2$}}\cdot \displaystyle \frac{1\text{ mol Sn}}{1 \text{ mol SnO$_2$}} \cdot\displaystyle \frac{118.71\text{ g Sn}}{1\text{ mol Sn}}[/tex]
Cancel like units:
[tex]=\displaystyle 4.5\cdot \frac{1000}{1}\cdot \displaystyle \frac{1}{150.708}\cdot \displaystyle \frac{1}{1} \cdot\displaystyle \frac{118.71\text{ g Sn}}{1}[/tex]
Multiply. Hence:
[tex]\displaystyle = 3544.5696...\text{ g Sn}[/tex]
Since we should have two significant figures:
[tex]=3500 \text{ g Sn}[/tex]
So, about 3500 grams of tin is produced from smelting 4.5 kg of tin(IV) oxide.
Answer:
3546g
Explanation:
start w/ tin (IV) oxide n elemental tin and oxygen gas are the only products of this reaction
SnO2 -> Sn + O2
Sn molecular wt: 119
O2 molecular wt: 32
SnO2 molecular wt: 119+32 = 151
so Sn / SnO2 wt ratio = 119 / 151
4.5 kilograms of tin (IV) oxide will produce:
= 4.5 * 119 / 151
= 3.546 kg
or 3546 grams of tin metal
no need to involve moles ;)
If the temperature of a volume of dieal gas ncreases for 100 to 200, what happens to the average kinetic energy of the molecules?
Answer:
It increases but less than double
Explanation:
As the temperature of a gas increase, the average kinetic energy of the gas increases. The kinetic energy of a gas is the thermal energy that the gas contains.
We know, the kinetic energy of an ideal gas is given by :
[tex]$V_{avg} = \sqrt{\frac{8R}{\pi M}}$[/tex]
where, R = gas constant
T = absolute temperature
M = molecular mass of the gas
From the above law, we get
[tex]$V_{avg} \propto \sqrt{T}$[/tex]
Thus, if we increase the temperature then the average kinetic energy of the ideal gas increases.
In the context, if the temperature of the ideal gas increases from 100°C to 200°C, then
[tex]$\frac{(V_{avg)_2}}{(V_{avg)_1}} =\sqrt{\frac{T_2}{T_1}}$[/tex]
[tex]$\frac{(V_{avg)_2}}{(V_{avg)_1}} =\sqrt{\frac{473.15}{373.15}}$[/tex]
[tex]$\frac{(V_{avg)_2}}{(V_{avg)_1}} =\sqrt{1.26}$[/tex]
[tex]$\frac{(V_{avg)_2}}{(V_{avg)_1}} =1.12$[/tex]
[tex]$(V_{avg})_2 = 1.12\ (V_{avg})_1$[/tex]
Therefore, [tex]$(V_{avg})_2 > (V_{avg})_1$[/tex]
Thus the average kinetic energy of the molecule increases but it increases 1.12 times which is less than the double.
Thus, the answer is " It increases but less that double".
Name the following molecule
Answer:
It is a Biological Molecule
Please help me order these bonds urgent
Answer:
From least polar covalent to most polar covalent;
S-I< Br-Cl < N-H< Te-O
From most ionic to least ionic
Cs-F> Sr-Cl> Li- N> Al-O
Explanation:
Electro negativity refers to the ability of an atom in a bond to attract the shared electrons of the bond towards itself.
Electro negativity difference between two atoms is a key player in the nature of bond that exists between any two atoms. A large difference in electron negativity leads to an ionic bond while an intermediate difference in electro negativity leads to a polar covalent bond.
Based on electro negativity differences, the bonds in the answer have been arranged in order of increasing polar covalent nature or decreasing ionic nature.
how does iron I differ from iron II
Answer:
Metals tend to form positive oxidation states. Here, Iron (I) has an oxidation state of +1 while Iron (II) has an oxidation state of +2. Similarly, Lead (I) has an oxidation state of +1 while Lead(II) has an oxidation state of +2. A change in oxidation state can rather cause significant changes in the compound.
Categorize the following reaction as an acid-base neutralization, precipitation, combination, decomposition, combustion, displacement, or disproportionation reaction.
Ba(C2H3O2)2(aq) + Na2CO3(aq) → BaCO3(s) + 2 NaC2H3O2(aq)
Answer:
Precipitation
Explanation:
Let's consider the balanced chemical equation between barium acetate and sodium carbonate to form barium carbonate and sodium acetate.
Ba(C₂H₃O₂)₂(aq) + Na₂CO₃(aq) → BaCO₃(s) + 2 NaC₂H₃O₂(aq)
Both products and reactants are salts. But, among the products, barium carbonate is solid. This allows us to classify it as a precipitation reaction.
how does lead resemble chromium?
Predict the Normality of H2SO4 if 75 ml of 96.6 % pure H2SO4 added to 425 ml water. The density of H2SO4 is 1.83 g/cm3?
Explanation:
Normality is one of the concentration terms.
It is expressed as:
[tex]N=\frac{mass of the substance}{equivalent mass}* \frac{1}{volume of solution in L.}[/tex]
The volume of the solution is 425 mL.
Mass of sulfuric acid given is:
[tex]mass=volume * purity* density\\ = 75 mL * 0.966 * 1.83 g/mL\\\\=132.5 grams\\[/tex]
The equivalent mass of sulfuric acid is 49.0g/equivalents
Hence, the normality of the given solution is:
[tex]N=\frac{132.5g}{49.0g/equi.} *\frac{1000}{425mL} \\Normality=6.36N[/tex]
Answer is: 6.36N.
Based on the "Reactivity in Substitution Reactions" experiment, which molecule would be expected to react the fastest using AgNO3 in water-ethanol ?
Answer:
C) EtOH 1% AgNO3
the -OH group cannot exhibit inductive effect? true/false, and reason for ur choice
Answer:
false
Explanation:
The inductive effects are know as the ability of the atom or a group to create polarization and electronic density long the covalent bond and it needs a higher density. The -OH group cannot exhibit the indictive effects as it becomes --O.Hazmat products warnings or labels allowed in fc
Answer:
The Hazmat products warnings or labels allowed in fc include:
1. Fully Regulated Aerosol Placard
2. Fully Regulated Flammable Solid Placard
3. Fully Regulated Flammable
4. Lithium-Ion/Metal Battery label
Explanation:
Hazmat products (including explosives, flammable liquids and solids, and gases, etc.) are classified as dangerous substances and materials that pose a risk to people during their storage, handling, or transportation. The requirement for this Hazmat classification is to show that the identified products require diligence, carefulness, and alertness in handling, transporting, and storing them. The reason for this is that mishaps can occur. Some of them can also cause fire outbreaks.
Name the functional group in the
following molecule:
Answer:
B. Aromatic
Explanation:
Functional groups are groups that differentiate a specific organic compound from others. A functional group determines the chemical property of the compound that possesses it.
For example, just like alkene and alcohol functional groups have characteristics double bond (=) and hydroxyl (OH) group respectively, the image in the attachment of this question has a BENZENE RING at the core of its structure, hence, the organic compound can be regarded to have an AROMATIC FUNCTIONAL GROUP.
Answer:
(B) aromatic
Explanation:
A step by step explanation
