If bovine haemoglobin has an extinction coefficient of 30910 L mol-1 cm-1 at 570 nm in PBS, what is the concentration of a solution reading an absorbance of 0.7?

Answer:

-It is considered the modern atomic model.

-It describes the probable locations of the electrons

Explanation:

edge 2020

The correct answer is:

The electron cloud model is another name used to describe the modern wave mechanical model of the atom.

It is the atomic model introduced by Erwin Schrodinger in 1927 based on the principles of quantum mechanics. It was an advancement over the Bohr model of the atom.

In this model, the atomic orbital is described as a region in space where there is a high probability of finding an electron. Hence, the electron is not found in specific orbits according to the Bohr model, rather, we describe the probability of finding the electron. This is the contemporary approach to the study of atomic structure.

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Answer:

Cesium (Cs)

Explanation:

This eliment has an ionization energy of 3,8939

Answer:54.82%

Explanation:

Percentage of carbon = mass of carbon in that compound/ mass of the compund *100

216/394*100 = 54.82%

Answer:

3

Explanation:

fe is iron ,O is oxygen and C is carbon

Answer:

4Fe + 6H2O + 3O2 -------> 4Fe(OH)3

Explanation:

The chemical reaction involves the fewest oxygen atoms is 4Fe + 6H2O + 302 4Fe(OH)3. Therefore, option B is correct.

The chemical reaction, the transformation of one or more chemicals (the reactants) into one or more distinct compounds (the products). Chemical elements or chemical compounds make up substances.

When atoms establish or break chemical bonds, chemical processes take place. Reactants are the substances that begin a chemical reaction, while products are the compounds that are created as a result of the reaction.

We can learn about a substance's qualities by studying chemical reactions. We can learn about a substance's chemical characteristics by looking at how it interacts with other substances. These characteristics can be utilized to recognize an unidentified sample.

Thus, option B is correct.

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Answer:

Q8) True

Q9) First ionization energy

Q10) Metal oxides

Explanation:

A common property of group one elements (alkali metals) is their combination with water to form basic solutions. E.g 2K(s)+2H2O(l)→2KOH(aq)+H2​(g).

The distance of the outermost electron in the atom from the nucleus is inversely related to the first ionization energy. As the distance between the outermost electron and the nucleus in group 17 elements gets larger, the corresponding first ionization energies of elements in the group gets smaller.

Group 1 elements can combine with oxygen to give metal oxides. E.g  4K + O2 --> 2 K2O

Answer: The concentration of Pb2+ in the anode compartment is [tex]1.74\times 10^{-6}M[/tex]

Explanation:

[tex]Sn^{2+}(aq)+Pb(s)\rightarrow Sn(s)+Pb^{2+}(aq)[/tex]

Here Pb undergoes oxidation by loss of electrons, thus act as anode. Sn undergoes reduction by gain of electrons and thus act as cathode.

[tex]E^0=E^0_{cathode}- E^0_{anode}[/tex]

Where both [tex]E^0[/tex] are standard reduction potentials.

[tex]E^0_{[Sn^{2+}/Sn]}=-0.14V[/tex]

[tex]E^0_{[Pb^{2+}/Pb]}=-0.13V[/tex]

[tex]E^0=E^0_{[Sn^{2+}/Sn]}- E^0_{[Pb^{2+}/Pb]}[/tex]

[tex]E^0=(-0.14-(-0.13)V=-0.01V[/tex]

Now using Nernst Eqn :

[tex]E=E^0-\frac{0.059}{n}\log\frac{[Pb^{2+}]}{[Sn^{2+}]}[/tex]

[tex]0.16=(-0.01)-\frac{0.059}{2}\log\frac{[Pb^{2+}]}{[1.00]}[/tex]

[tex]0.17=-0.0295\log\frac{[Pb^{2+}]}{[1.00]}[/tex]

[tex]-5.76=\log\frac{[Pb^{2+}]}{[1.00]}[/tex]

[tex]1.74\times 10^{-6}=\frac{[Pb^{2+}]}{[1.00]}[/tex]

[tex][Pb^{2+}]=1.74\times 10^{-6}[/tex]

The energy produced by burning : -32.92 kJ

Delta H reaction (ΔH) is the amount of heat change between the system and its environment

(ΔH) can be positive (endothermic = requires heat) or negative (exothermic = releasing heat)

The enthalpy and heat(energy) can be formulated :

[tex]\tt \Delta H=\dfrac{Q}{n}\rightarrow n=mol[/tex]

The enthalpy of combustion of naphthalene (MW = 128.17 g/mol) is -5139.6 kJ/mol.

The energy released for 0.8210 g of naphthalene :

[tex]\tt Q=\Delta H\times n\\\\Q=-5139.6~kJ/mol\times \dfrac{0.8210~g}{128.17~g/mol}~\\\\Q=-32.92~kJ[/tex]

Answer:

H=mc∆T

H=15×4.18×20

H=1254J

Answer:

No because a straw is plastic look at it by this was, the energy used to create one metal straw is roughly equivalent to creating 90 plastic straws, and also produces carbon emissions equivalent to 150 plastic straws. This may not seem like a lot, but in order to offset the environmental impact of creating a metal straw, it must be used over 150 times

Explanation:

Answer:

90.4 mL

Explanation:

Step 1: Given data

Step 2: Calculate the final volume of the gas

According to Boyle's law, the volume of a gas is inversely proportional to the pressure. We can calculate the final volume of the gas using the following expression.

P₁ × V₁ = P₂ × V₂

V₂ = P₁ × V₁ / P₂

V₂ = 721 mmHg × 113 mL / 901 mmHg

V₂ = 90.4 mL

Answer:

Mn

Explanation:

The cation in the chemical formula MnSe is the Mn specie.

The theoretical yield (in kilograms) of water produced from this reaction : 0.285 kg

Reaction

2C₁₂H₂₄O₁₁ + 25O₂ → 24CO₂ + 24H₂O

mass of C₁₂H₂₄O₁₁ - isomaltitol = 454 g

mol C₁₂H₂₄O₁₁(MW=344.31 g/mol) :

[tex]\tt mol=\dfrac{mass}{MW}\\\\mol=\dfrac{454}{344.31 g/mol}\\\\mol=1.319[/tex]

mol H₂O based on C₁₂H₂₄O₁₁ as limiting reactant(O₂-oxygen as an excess)

From the equation above, mol ratio of C₁₂H₂₄O₁₁  : H₂O = 2 : 24, so mol H₂O:

[tex]\tt mol~H_2O=\dfrac{24}{2}\times 1.319=15.828[/tex]

then mass H₂O (MW=18 g/mol) :

[tex]\tt mass=mol\times MW\\\\mass=15.828\times 18=284.904~g=0.285~kg[/tex]

Answer:

a) 2.01 g

Explanation:

First we convert 0.0302 mol AgNO₃ to Na₂CO₃ moles, in order to calculate how many Na₂CO₃ moles reacted:

So the remaining Na₂CO₃ moles are:

Finally we convert Na₂CO₃ moles into grams, using its molar mass:

The closest answer is option a).

Answer:

76.1%

Explanation:

The reaction that takes place is:

First we determine how many moles of each reactant were added:

Thus K₂SO₄ is the limiting reactant.

Using the moles of the limiting reactant we calculate how many moles of BaSO₄ would have been produced if the % yield was 100%:

Then we convert that theoretical amount into grams, using the molar mass of BaSO₄:

Finally we calculate the % yield:

Answer: Two equatorial positions so as to minimize the repulsion.

Explanation:

Formula used for calculating number of electrons :

[tex]\frac{1}{2}[V+N-C+A][/tex]

where,

V = number of valence electrons present in central atom  = 8

N = number of monovalent atoms bonded to central atom = 4

C = charge of cation  = 0

A = charge of anion  = 0

Now we have to determine the hybridization of the [tex]XeF_4[/tex]   molecule.

[tex]\frac{1}{2}[8+4-0+0]=6[/tex]

Bond pair electrons = 4

Lone pair electrons = 2

The number of electrons are 6 that means the hybridization will be [tex]sp^3d^2[/tex] and the electronic geometry of the molecule will be octahedral.

The molecular geometry will be square planar as two alternate positio ns will be occupied by lone pair of electrons so as to minimize the repulsion.

Answer:

C

Explanation:

I hope that helps!!! it kinda gave you the answer though

Answer:

Explanation:

1) The ΔH shows the heat of reaction of the reaction illustrated in the question and the negative sign shows the reaction is an exothermic reaction, meaning heat is released in this reaction. The amount of heat released in this reaction is 851.5 kilojoules per mole of Al₂O₃ produced.

2) The thermal energy of this reaction is however very low when compared to the energy released when 2 moles of protons and 2 moles of neutrons combine to form 1 mole of alpha particles. This is because, the reaction illustrated in the (1) above is a normal chemical reaction while the one that involves the protons and neutrons (as described in this section 2) is a nuclear reaction which involves large amount of energy. Nuclear reactions usually involve way larger amount of energy than ordinary chemical reactions.

1. 0.33 M

2. 0.278 M

Molarity is a way to express the concentration of the solution

Molarity shows the number of moles of solute in every 1 liter of solute or mmol in each ml of solution

[tex]\large{\boxed {\bold {M ~ = ~ \frac {n} {V}}}[/tex]

Where

M = Molarity

n = Number of moles of solute

V = Volume of solution

1. 0.350 mol of NaOH in 1.05 L of solution.

n=0.35

V=1.05 L

Molarity :

[tex]\tt M=\dfrac{0.35}{1.05}=0.33[/tex]

2. 14.3 g of NaCl in 879 mL of solution.

mol NaCl(MW=58.5 g/mol) :

[tex]\tt mol=\dfrac{mass}{MW}\\\\mol=\dfrac{14.3~g}{58.5~g/mol}=0.244[/tex]

Molarity :

[tex]\tt M=\dfrac{0.244}{0.879~L}\\\\M=0.278[/tex]

Answer:

D. 2 NO3(aq)+Ca2+

Explanation:

Reaction of calcium nitrate and potassium phosphate produce calcium phosphate and potassium nitrate. The net ionic equation for this is written as : [tex]3 Ca^{2+} (aq) +2PO_{4} ^{3-} (aq) \rightarrow Ca_{3}(PO_{4} )_{2} (s)[/tex]. Thus option C is correct.

What is double displacement reaction?

In a double displacement reaction, two species or groups in reactant side are displaced in the products.

In a balanced chemical equation, all the reactants have to be in proper stochiometric ratio and the states of all species are mentioned in brackets.

In an ionic equation all the ions and charges are balanced both side and the number of each elements on both side too. The net ionic equation represents the formation of a solid product from its ions.

The balanced molecular equation and complete ionic equation are written for the given  reaction below:

[tex]3 Ca (NO_{3})_{2} (aq)+ 2K_{3} PO_{4} (aq) \rightarrow Ca_{3}(PO_{4} )_{2} (s) + 6 KNO_{3}(aq)[/tex]

[tex]3 Ca^{2+} (aq) +6 NO_{3}^{-} + (aq)+ 6K^{+} + (aq) 2PO_{4} ^{3-} (aq) \rightarrow Ca_{3}(PO_{4} )_{2} (s) + 6 NO_{3}^{-} (aq)+ 6K^{+} (aq)[/tex]

Now when the same species on both side is cancelled, then the net ionic equation is written as:

[tex]3 Ca^{2+} (aq) +2PO_{4} ^{3-} (aq) \rightarrow Ca_{3}(PO_{4} )_{2} (s)[/tex]

Therefore, the correct et ionic equation is option c.

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Answer:

You can not make the observation in the lab

Explanation:

We must know the amount of Nitrogen-16 that remains after 57 seconds before we can make our conclusion.

Hence, from;

N/No = (1/2)^t/t1/2

Where;

N = amount of Nitrogen-16 present after 57 seconds

No = 100g of Nitrogen-16 originally present

t = 57 seconds

t1/2 = half life of Nitrogen-16 which is 7.13 seconds

Substituting values;

N/100 = (1/2)57/7.13

N/ 100 =(1/2)^8

N/100 = 1/256

256N = 100

N = 100/256

N = 0.39 g

You can not make the observation because you need at least 5g of Nitrogen-16 and only 0.39 g is left after 57 seconds.

The minimum amount of sample required has been 5 grams, while the remaining sample has been 0.39 grams. Thus, it has not been possible to make the observations.

The half life can be defined as the time required for the sample to reduce to half of its initial concentration. The half life can be given as:

Amount remained = Initial amount [tex]\rm \times\;\dfrac{1}{2}^\dfrac{time}{Half-life}[/tex]

The half life of nitrogen 16 has been 7.13 second.

The initial concentration of the sample has been 100 grams.

The concentration of sample remained after 57 seconds has been:

Amount remained = 100 [tex]\rm \times\;\dfrac{1}{2}^\dfrac{57\;sec}{7.13\;sec}[/tex]

Amount remained = 0.39 grams.

The amount of sample remained after 57 seconds has been 0.39 grams.

The amount of sample required for the analysis has been 5 grams, after 57 seconds only 0.39 grams of sample has been remaining. Thus, the student will not be able to made analysis of nitrogen-16.

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Answer:

530.835 g

Explanation:

First we convert 244 g of benzoic acid (C₇H₆O₂) to moles, using its molar mass:

Theoretically, one mol of ethyl benzene would produce one mol of benzoic acid. But the experimental yield tells us that one mol of ethyl benzene will produce only 0.4 moles of benzoic acid.

With the above information in mind we convert 2.00 moles of benzoic acid into moles of ethyl benzene:

Finally we convert moles of ethyl benzene (C₈H₁₀) into grams, using its molar mass:

Answer:

Thermal energy

Explanation:

When gasoline, coal, batteries and logs are all burn they transform chemical energy to thermal energy.

The chemical energy is the energy held between chemical chains and bonds within an atom.

Answer:

b its radiant energy that heats up the earth.

Explanation:

Answer:

The answer is D

Explanation:

Heat from the Earth's core and radiation from the Sun is transferred to the surface of the Earth by conduction. The warm land and water radiates infrared, some of which is absorbed by the atmosphere, adding to its thermal energy.

Answer:

A and B

Explanation:

Trust me I just did it on a p e x

Answer: he’s correct it’s d and b for me but it’s the same answers

Explanation:

Answer:

Explanation:

The mass of the football can be found by using the formula

[tex]m = \frac{f}{a} \\ [/tex]

f is the force

a is the acceleration

From the question we have

[tex]m = \frac{600}{30} = \frac{60}{3} \\ [/tex]

We have the final answer as

Hope this helps you