Answer:
Have you ever touched a fish? Most fish will feel a bit rough - due to their scales. Some, like sharks, will feel like sandpaper. Even fish with small, smoother scales will feel a bit like that. Amphibians don’t have scales, and most species will be wet to some degree - they have to keep their skin moist or they’ll die. A few groups, like toads and newts, have rougher skin, which is heavier and thicker, which allows them to retain moisture better away from water.
Functionally, the big thing about amphibian skin is that it is semi-permeable. Amphibians can breathe through their skin - all amphibians can get some oxygen through their skin, but some species of salamanders get all their oxygen that way - they have no lungs or gills. The skin can also allow water in - sort of like a paper towel. The bad thing is that other chemicals can pass through the skin, too - pollutants and other chemicals tend to affect amphibians far more than they do other groups.
Amphibians also shed their skin - fish do not. People don’t tend to see frogs shedding their skin often, though, since they eat it to regain nutrients and other resources in the skin.
Finally, since amphibian skin offers no defense against predators in the way that scales do, and limited barrier against disease the way non-amphibian skin does (shedding helps), the skin of many amphibians contain toxins, and some of them have anti-fungal properties (typically due to symbiotic bacteria). Many species have evolved chemical defenses in the skin, while others have glands that produce toxins that can be secreted outside of the skin.
The skin can withstand dessication more than the fish.
They have moist skin used as respiratory surface during deep sleep / hibernation.
They have moist skin due to secretion of mucus by glands under the skin.
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The homework question reads:
"A sample of gas in a cylinder of volume 3.42 L at 298 K
and 2.57 atm expands to 7.39 L by two different pathways.
Path A is an isothermal, reversible expansion. Path B has two
steps. In the fi rst step, the gas is cooled at constant volume to
1.19 atm. In the second step, the gas is heated and allowed to
expand against a constant external pressure of 1.19 atm until
the final volume is 7.39 L. Calculate the work for each path.
Answer:
Explanation:
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Answer : The work done for path A and path B is -685.3 J and -478.1 J respectively.
Explanation :
To calculate the work done for path A :
First we have to calculate the moles of the gas.
where,
= initial pressure of gas = 2.57 atm
= initial volume of gas = 3.42 L
n = moles of gas = ?
R = gas constant = 0.0821 atm.L/mol.K
T = temperature of gas = 298 K
Now put all the given values in the above formula, we get:
According to the question, this is the case of isothermal reversible expansion of gas.
As per first law of thermodynamic,
where,
= internal energy
q = heat
w = work done
As we know that, the term internal energy is the depend on the temperature and the process is isothermal that means at constant temperature.
So, at constant temperature the internal energy is equal to zero.
The expression used for work done will be,
where,
w = work done on the system = ?
n = number of moles of gas = 0.359 mole
R = gas constant = 8.314 J/mole K
T = temperature of gas = 298 K
= initial volume of gas = 3.42 L
= final volume of gas = 7.39 L
Now put all the given values in the above formula, we get :
Thus, the work done of path A is, -685.3 J
To calculate the work done for path B :
The formula used for isothermally irreversible expansion is :
where,
w = work done
= external pressure = 1.19 atm
= initial volume of gas = 3.42 L
= final volume of gas = 7.39 L
Now put all the given values in the above formula, we get :
Thus, the work done of path B is, -478.1 J
Na2CO3 + CaCl2•2H2O -> CaCO3 + 2NaCl + 2H2O
Calculate how many moles of CaCl2•2H2O are present in 1.50 g of CaCl2•2H2O and then calculate how many moles of pure CaCl2 are present in 1.50 g of CaCl2•2H2O. Then determine how many grams of Na2CO3 are necessary to reach stoichiometric quantities.
For CaCl2 I got 0.0135 mol but I have seen some put 0.0102 mol. Which is it?
For the initial mol of Na2CO3 I got 0.0102 mol but again I’m not sure if I’m right.
For the grams of Na2CO3 I got 1.08 g
Can someone help me figure out if I have this correct?
Answer:
See explanation
Explanation:
Number of moles = reacting mass/molar mass
Number of moles of CaCl2•2H2O = 1.50 g/147.02 = 0.0102 moles
From the equation;
Na2CO3 + CaCl2•2H2O -> CaCO3 + 2NaCl + 2H2O
We can see is 1:1
1 mole of Na2CO3 reacts with 1 mole of CaCl2•2H2O
x moles of Na2CO3 reacts with 0.0102 moles of CaCl2•2H2O
x = 1 × 0.0102 moles/1
x = 0.0102 moles of Na2CO3
Mass of Na2CO3 = 0.0102 moles of Na2CO3 × 106g/mol = 1.08 g of Na2CO3
Compute the equilibrium constant for the spontaneous reaction between Cd2 (aq) and Zn(s).
Answer:
Kc = [Zn²⁺] / [Cd²⁺]
Explanation:
Let's consider the spontaneous redox reaction between Cd²⁺ and Zn.
Cd²⁺(aq) + Zn(s) ⇄ Cd(s) + Zn²⁺(aq)
The equilibrium constant, Kc, is the ratio of the equilibrium concentrations of products over the equilibrium concentrations of reactants each raised to the power of their stoichiometric coefficients. It only includes gases and aqueous species.
Kc = [Zn²⁺] / [Cd²⁺]
5.60g of glyceraldehydes was dissolved in 10ml of a solvent and placed in a 50mm cell if the rotation is 1.74 calculate the specific rotation?
Answer:
6.214 degrees-mL/gdm
Explanation:
The specific rotation α' = α/LC where α = observed rotation, L = length of tube and C = concentration of solution.
Given that α = 1.74, L = length of cell = 50 mm = 0.50 dm and C = m/V where m = mass of glyceraldehyde = 5.60 g and V = volume = 10 ml
So, C = m/V = 5.60 g/10 ml = 0.560 g/ml
Since α' = α/LC
substituting the values of the variables into the equation, we have
α' = α/LC
α' = 1.74/(0.50 dm × 0.560 g/ml)
α' = 1.74/(0.28 gdm/l)
α' = 0.006214 °mL/gdm
α' = 6.214 °mL/gdm
α' = 6.214 degrees-mL/gdm
Use the Ka values for weak acids to identify the best components for preparing buffer solutions with the given pH values.
Name Formula Ka
Phosphoric acid H3PO4 7.5 x 10^-3
Acetic acid CH3COOH 1.8 x 10^-5
Formic acid HCOOH 1.8 x 10^-4
pH 1.9 =_________
pH 5.0 = ________
pH 3.9= ________
Answer:
pH= 1.9 then [tex]H_{3} PO_{4}[/tex]
pH = 5.0 , [tex]CH_{3} COOH[/tex]
pH = 3.9 , HCOOH
As we know range left [tex]pH= pKa+/- 1[/tex]
You should set out support, like a cork ring or clamp, before removing the glassware from a glassware kit to place the glassware in and to stop it from _________. Thoroughly check that the glasswar is________ and that it does not have any _______before using it.
Answer:
(A) Slipping and breaking
(B) Clean and dry
(C) Cracks
Explanation:
This describes the process of unpacking a glassware for use.
You should set out support like a cork ring or clamp (these are simple machines that'll hold the glassware in place) before removing the glassware from a glassware kit; to place the glassware in and to stop it from slipping and breaking.
Thoroughly check that the glassware is clean and dry and that it does not have any cracks, before using it.
4) In water, Vanillin, C8H8O3, has a solubility of 0.070 moles of vanillin per liter of solution at 25C. What will be produced if 5.00 g of vanillin are added to 1 L of water at 25 C
Answer:
An unsaturated solution.
Explanation:
Hello there!
In this case, according to the given information, it turns out possible for us to firstly realize we need to calculate the grams of vanillin in 0.070 moles by using its molar mass of 152.15 g/mol:
[tex]m=0.070mol*\frac{152.15 g}{1mol} =10.65g[/tex]
Thus, since the solubility is 10.65 g per 1 L of solution, we can notice 5.00 g will complete dissolve and produce an unsaturated solution.
Best regards!
Write the structure of methanamine
Answer: CH3NH2
Explanation:
Sometimes in lab we collect the gas formed by a chemical reaction over water . This makes it easy to isolate and measure the amount of gas produced.
Suppose the CO, gas evolved by a certain chemical reaction taking place at 50.0°C is collected over water, using an apparatus something like that in the sketch, and the final volume of gas in the collection tube is measured to be 132. mL. Calculate the mass of CO, that is in the collection tube. Round your answer to 2 significant digits.
Answer:
0.17 g
Explanation:
Since the volume of gas collected is 132 mL, we need to find the number of moles of gas present in 132 mL.
So, number of moles, n = volume of gas, v/molar volume, V
n = v/V where v = 132 mL = 0.132 L and V = 22.4 L
So, substituting the values of the variables into the equation, we have
n = v/V
n = 0.132 L/22.4 L
n = 0.005893 mol
We then need to calculate the molar mass of CO, M = atomic mass of carbon + atomic mass of oxygen = 12 g/mol + 16 g/mol = 28 g/mol
Also, number of moles of gas, n = m/M where m = mass of CO and M = molar mass of CO
m = nM
m = 0.005893 mol × 28 g/mol
m = 0.165004 g
m ≅ 0.17 g to 2 significant digits
A covalent bond is formed by the following process
Answer:
Covalent bonding occurs when pairs of electrons are shared by atoms.
Explanation:
Atoms will covalently bond with other atoms in order to gain more stability, which is gained by forming a full electron shell. By sharing their outer most (valence) electrons, atoms can fill up their outer electron shell and gain stability.
how many of the electrons in a molecule of ethane are not involved in bondind
Ethane consists of 6C−H bonds and 1C−C bond. Total number of bonds is 7. Each bond is made up of two electrons
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any two functions of crystals
Answer:
1. Participating in calcium homeostatis storage of calcium.
2. High capacity calcium (Ca) regulation and protection against herbivory
[tex]\large \boxed{\sf 2 \: functions \: of \: crystals \: are :- } [/tex]
_________________
⟹
[tex] \sf \: \underline{ Calcium \: oxalate \: (CaOx) \: crystals} \: are \: distributed \: \\\sf among \: all \: taxonomic \: levels \\ \sf\: of \: photosynthetic \: organisms \: from \\ \sf \: small \: algae \: to \: angiosperms \: and \: giant \: gymnosperms .[/tex]
__________________
⟹
[tex]\sf Bone \: is \: mostly \: made \: of \: \underline{mineral \: crystals} \: \\ \sf and \: the \: protein \: collagen. \: The \: mineral \: crystals \: bone \\ \sf\: provide \: strength \: and \: rigidity \: for \: the \: matrix \: upon \: \\ \sf \: and \: within \: which \: they \: are \: deposited.[/tex]
A compound, C20H28O, produces a 1H NMR spectrum with 11 distinct signals. The steps made by the integral trace measure 52, 17, 17, 26, 17, 25, 26, 9, 9, 35, and 8 mm. Complete the following table.
Integral # Products
52 mm
17 mm
17 mm
26 mm
17 mm
25 mm
26 mm
35 mm
8 mm
Solution :
The smallest integer value represents the smaller number of protons.
In this case, in the given values, the smallest numbers are 8 mm and 9 mm, so both contains 1H each. Then next highest value is 17 mm, which contains 1H more. Thus 17 mm contains 2H each. Then the next highest is 25 mm and 26 mm which contains 3M each and so on.
Thus the tables is :
Integral Protons
52 mm [tex]6[/tex]
17 mm [tex]2[/tex]
17 mm 2
26 mm 3
17 mm 2
25 mm 3
26 mm 3
9 mm 1
9 mm 1
35 mm 4
8 mm 1
Each set of quantum numbers to the correct sub shell description
Elements that have the same number of electron rings are ?
Answer:
are in the same orbital
Explanation:
Answer:
are in the same orbit
Explanation:
How many grams of P4O10 (292.88 g/mol) form when phelpsphorous (P4, 125.52 g/mol) reacts with 16.2 L of O2 (33.472 g/mol) ) at standard temperature and pressure
Answer:
40.5 g of P₄O₁₀ are produced
Explanation:
We state the reaction:
P₄ + 5O₂ → P₄O₁₀
We do not have data from P₄ so we assume, it's the excess reactant.
We need to determine mass of oxygen and we only have volumne so we need to apply density.
Density = mass / volume, so Mass = density . volume
Denstiy of oxygen at STP is: 1.429 g/L
1.429 g/L . 16.2L = 23.15 g
We determine the moles: 23.15 g . 1mol / 33.472g = 0.692 moles
5 moles of O₂ can produce 1 mol of P₄O₁₀
Our 0.692 moles may produce (0.692 . 1)/ 5 = 0.138 moles
We determine the mass of product:
0.138 mol . 292.88 g/mol = 40.5 g
What enzyme below is an exoenzyme?
A. Casease
B. Citrase
C. Catalase
D. Oxidase
The compound IF5 contains Question 16 options: polar covalent bonds with partial negative charges on the F atoms. ionic bonds. polar covalent bonds with partial negative charges on the I atoms. nonpolar covalent bonds.
Answer:
See explanation
Explanation:
The molecule IF5 possesses five I-F polar bonds. However, the presence of polar bonds does not automatically imply that the molecule will be polar.
The geometry of the molecule is very important in determining the polarity of a compound. Since IF5 has a lone pair of electrons, the molecule is bent and as such there is a permanent dipole moment created in the molecule thereby making IF5 polar in nature.
It is found that, when a dilute gas expands quasistatically from 0.40 to 5.0 L, it does 210 J of work. Assuming that the gas temperature remains constant at 300 K, how many moles of gas are present
Answer:
[tex]n=0.033mole[/tex]
Explanation:
From the question we are told that:
Initial volume [tex]V_1=0.40L[/tex]
Final Volume[tex]V_2=5.0L[/tex]
Work [tex]W=210J[/tex]
Temperature [tex]T=300k[/tex]
Generally the equation for Ideal gas is mathematically given by
[tex]W=nRTIn\frac{V_2}{V_1}[/tex]
[tex]n=\frac{W}{RTIn\frac{V_2}{V_1}}[/tex]
[tex]n=\frac{210}{8.32*300In\frac{5.0}{0.4}}[/tex]
[tex]n=0.033mole[/tex]
For the following list of acids, rank the acids in strength from weakest acid to strongest acid.
a. FCH2OH
b. F2CHOH
c. CH3OH
d. F3COH
Answer:
CH3OH < FCH2OH < F2CHOH < F3COH
Explanation:
Let us recall that, for a carboxylic acid, the dissociation of the acid yields;
RCOOH ⇄RCOO^- + H^+
The ease of dissociation and release of the hydrogen ion depends on the nature of the group designated R.
When R is is a highly electronegative element, the -I inductive effect causes the hydrogen to become less tightly held by the C-Cl bond.
As the number of electron withdrawing substituents increaseses, the acid ionizes much more and becomes stronger.CH3OH < FCH2OH < F2CHOH < F3COH
Hence, the order of decreasing acid strength is;
Solid aluminum (AI) and oxygen (0) gas react to form solid aluminum oxide (AIO). Suppose you have 7.0 mol of Al and 13.0 mol of o, in a reactor. Suppose as much as possible of the Al reacts. How much will be left? Round your answer to the nearest 0.1 mol mol 0.
Answer:
[tex]n_{O_2}^{leftover}=7.7mol[/tex]
Explanation:
Hello there!
In this case, according to the given information, it turns out firstly necessary for us to set up the corresponding chemical equation:
[tex]4Al+3O_2\rightarrow 2Al_2O_3[/tex]
In such a way, we calculate the moles of aluminum consumed by 13.0 moles of oxygen in the reaction, by applying the 4:3 mole ratio between them:
[tex]n_{Al}=13.0molO_2*\frac{4molAl}{3molO_2} =17.3molAl[/tex]
This means that Al is actually the limiting reactant and oxygen is in excess, for that reason we calculate the moles of oxygen consumed by 7.0 moles of aluminum:
[tex]n_{O_2}=7.0molAl*\frac{3molO_2}{4molAl} =5.3molO_2[/tex]
Thus, the leftover of oxygen is:
[tex]n_{O_2}^{leftover}=13.0mol-5.3mol\\\\n_{O_2}^{leftover}=7.7mol[/tex]
Whereas all the aluminum is assumed to be consumed.
Regards!
To determine the concentration of an EDTA solution, 4.11 g of Zn metal was used. The volume of EDTA solution needed to reach the endpoint was 28.26 mL. What was the concentration (in molarity) of the EDTA solution?
Answer:
2.23M
Explanation:
Molarity of a solution is calculated thus
Molarity = number of moles (n) ÷ volume (V)
According to this question, 4.11g of Zn metal was used in order to reach a volume of EDTA solution of 28.26 mL.
28.26mL = 28.26/1000
= 0.02826L
Using mole = mass/molar mass to calculate no. of moles of Zn
Mole = 4.11/65.4
mole = 0.0628mol
Molarity = 0.0628 ÷ 0.02826
Molarity = 2.23M
The concentration of the EDTA solution used is 2.23M
Classify the processes as endothermic or exothermic.
a. Ice melting
b. Water condensing on surface
c. Baking a cake
d. The chemical reaction inside an instant cold pack.
e. A car using gasoline
endothermic absorbs heat
exothermic gives heat
a. endothermic
b. exothermic
c. endothermic
d. exothermic
a. Ice melting - endothermic
b. Water condensing on the surface - exothermic
c. Baking a cake - endothermic
d. The chemical reaction inside an instant cold pack - endothermic
e. A car using gasoline - exothermic
What is an exothermic and endothermic reaction?An exothermic reaction can be described as a thermodynamic chemical reaction that emits energy from the system to its surroundings usually in the form of light, heat, or sound.
While an endothermic reaction can be described as an opposite of an exothermic reaction where the energy gains in the form of heat. In exothermic chemical reactions, the bond energy is transformed into thermal energy.
In exothermic reactions, the reaction happens the form of the kinetic energy of molecules when the energy is released. The release of energy is due to the electronic transition of electrons from one energy level to another.
The burning of gasoline, and water condensation is also an exothermic reaction in which energy is released while ice melting and baking cake is an endothermic reaction.
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Please explain how to do it as well!
Write a complete, balanced equation for the following reactions:
a) The combustion of C₆H₁₂O (teachers note: You figure out products).
b) Aqueous ferric iron (III) sulfate plus barium hydroxide (teachers note: You figure out the products).
Answer:
a) C₆H₁₂O + 8.5 O₂ ⇒ 6 CO₂ + 6 H₂O
b) Fe₂(SO₄)₃ + 3 Ba(OH)₂ ⇒ 3 BaSO₄ + 2 Fe(OH)₃
Explanation:
a) A combustion is a reaction of a compound with oxygen to produce carbon dioxide and water. The corresponding equation is:
C₆H₁₂O + O₂ ⇒ CO₂ + H₂O
We will start balancing C atoms by multiplying CO₂ by 6 and H atoms by multiplying H₂O by 6.
C₆H₁₂O + O₂ ⇒ 6 CO₂ + 6 H₂O
Then, we get the balanced equation by multiplying O₂ by 8.5.
C₆H₁₂O + 8.5 O₂ ⇒ 6 CO₂ + 6 H₂O
b) This is a double displacement reaction of the general structure:
Salt 1 + Base 1 = Salt 2 + Base 2
The corresponding equation is:
Fe₂(SO₄)₃ + Ba(OH)₂ ⇒ BaSO₄ + Fe(OH)₃
First, we will balance Fe atoms by multiplying Fe(OH)₃ by 2 and S atoms by multiplying BaSO₄ by 3.
Fe₂(SO₄)₃ + Ba(OH)₂ ⇒ 3 BaSO₄ + 2 Fe(OH)₃
Then, we will get the balanced equation by multiplying Ba(OH)₂ by 3.
Fe₂(SO₄)₃ + 3 Ba(OH)₂ ⇒ 3 BaSO₄ + 2 Fe(OH)₃
Answer:
a.[tex]\bold{C_{6}H_{12}O_{6}\rightarrow 6CO_{2}+6H_{2}O}[/tex]
△H=−72 kcal
The energy required for production of 1.6 g of glucose is [molecular mass of glucose is 180 gm]
b.
[tex]\bold{Fe_{2}(SO_{4})_{3}+3Ba(OH)_{2}\rightarrow 3BaSO_{4}+2Fe(OH)_{3}}[/tex]
The iron(III) ions and chloride ions remain aqueous and are spectator ions in a reaction that produces solid barium sulfate.
1. Most of the chemicals included in your General Chemistry Lab kit can be discarded down a drain. Describe a situation in which you would need to neutralize a chemical before discarding down a drain.
Answer: Chemicals like acids and bases are harmful and must be neutralized before draining.
Explanation:
A strong acid or strong base is required to be diluted or neutralized before it is discarded in the drain as if is discarded without diluting and neutralization it can spill and splash from sink or drain and can harm people in chemistry lab, moreover the fumes of the discarded chemical on spilling can cause respiratory tract burning and can even cause fire hazard so it must be converted into less harmful form and then must be drained.
How many moles in 3.30g of iron
The answer below is correct but to give you the process, here it is:
Molar mass of iron, Fe = 55.85 g/mol
3.30g/(55.85 g/mol) = 0.0591 mol
Classify each of the following chemical reaction as a synthesis, decomposition, single-displacement, or double-displacement reaction. Drag the appropriate items to their respective bins.
CH3Br → CH3(g) + Br(g)
Zn(s) + CoCl2(aq) → ZnCl2(aq)
First Reaction is a Decomposition reaction as a single reactant hets decompoesed to form two products.Second reaction is a Synthesis reaction as two Reactant reacts together to form one product.
What is Decomposition Reaction ?Decomposition reactions are processes in which chemical species break up into simpler parts.
Usually, decomposition reactions require energy input.
Hence, First Reaction is a Decomposition reaction as a single reactant hets decompoesed to form two products.Second reaction is a Synthesis reaction as two Reactant reacts together to form one product.
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A system receives 425 J of heat from and delivers 425 J of work to its surroundings. What is the change in internal energy of the system (in J)?
Answer:
0 J
Explanation:
Applying,
ΔE = q+w................ Equation 1
Where ΔE = change in internal energy of the system, q = Heat of the system, w = work of the system.
Note: q is positive, while w is negative
From the question,
Given: q = 425 J, w = -425 J
Substitute these values into equation 1
ΔE = 425-425
ΔE = 0 J
Hence the change in internal energy of the system is 0 J
42 Organic compound may have names ending in -ane, -ene, -ol or -oic acid. How many of these endings indicate the compounds contain double bonds in their molecules? * (1 Point)
Answer: Organic compounds ending with the name (-ene) indicate that the compounds contain double bonds in their molecules.
Explanation:
Organic compounds are those molecules that contains carbon atoms (as their main element), hydrogen and oxygen which are usually present. The presence of numerous organic compounds is due to the following properties of carbon:
--> the exceptional ability of carbon atoms to catenate, that is, to combine with one another to form straight chains, branched chains or ring compounds containing many carbon atoms.
--> The ease with which carbon combines with hydrogen, oxygen, Nitrogen and halogens
--> The ability of carbon atoms to form single, DOUBLE or triple bonds.
The organic compound that has the name ending with -ene are known as the alkenes. The members of the alkene series are formed from the alkanes by the removal of two hydrogen atoms and the introduction of a DOUBLE BOND in the carbon chain. They are named after the corresponding alkanes by changing the -ane ending to -ene.
Note: the systematic name of a compound is formed from the root hydrocarbon by adding a suffix and prefixes to denote the substitution of the hydrogen atoms.
The decomposition of ethyl amine, C2H5NH2, occurs according to the reaction: C2H5NH2(g)⟶C2H4(g)+NH3(g) At 85∘C, the rate constant for the reaction is 2.5 x 10-1 s-1. What is the half-life (in sec) of this reaction?
Answer:
2.772 seconds
Explanation:
Given that;
t1/2 = 0.693/k
Where;
t1/2 = half life of the reaction
k= rate constant
Note that decomposition is a first order reaction since the rate of reaction depends on the concentration of one reactant
t1/2 = 0.693/2.5 x 10-1 s-1
t1/2= 2.772 seconds
