who discovered copper

Answer:

CH₃CH₂-CH₂CH₃

Explanation:

When an alkene, R-CH=CH-R reacts with H₂ in a Pt catalyst, the analogue alkane, R-CH₂-CH₂-R, is produced (Hydrogenation of alkenes via Pt/Pd catalyst)

Thus, the reaction of CH₃CH=CHCH₃ with H₂ under a platinum catalyst produce:

The analogue alkane

The addition of hydrogen to CH3CH=CHCH3 leads to the formation of CH3CH2CH2CH3.

An alkene is a hydrocarbon that contains a C=C double bond. An alkene undergoes addition reaction in which a molecule is added across the double bond to form a saturated hydrocarbon.

The addition of H2 to CH3CH=CHCH3 yields butane as shown in the image attached. The platinum metal serves a catalyst in the reaction.

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Answer:

459.6kj

Explanation:

the chemical equation =

3mn(s) + 2CO2(g) --- Mn3O4(s)

we have change in H to be -1378.83

we are required to find the amount of heat that is liberated for a mole of manganese.

3 moles of manganese = -1378.83

1 mole of manganese = ?

when we cross multiply, we will have a ratio that we will use to find this amount

1378.83/3 = 459.6kj

Answer:

Explanation:

To find the number of moles we must first find the molar mass of LiCL

From the question

mass = 0.550g

M(Li) = 6 Cl = 35.5

Molar mass of LiCL = 6 + 35.5 = 41.5 g/mol

Then we use the formula

[tex]n = \frac{m}{M} [/tex]

where

n is the number of miles

m is the mass

M is the molar mass

So we have

[tex]n = \frac{0.550}{41.5} [/tex]

We have the final answer as

Hope this helps you

Answer:

82.5 metres

Explanation:

speed=330m|s

initial time taken =0.5÷2=0.25

distance=speed×time

330m|s × 0.25s = 82.5m

Answer:

1.pp

2.cp

3.pp

4.pp

5.pp

6.pp

Answer:

solids, liquids, gases, or plasma

Explanation:

In chemistry, a chemical substance is a form of matter that has constant chemical composition and characteristic properties. It cannot be separated into components without breaking chemical bonds. Chemical substances can be solids, liquids, gases, or plasma

Answer:

b. H-3

Explanation:

The half life of the following isotopes is given as;

a. 0-19

26.88 seconds

b. H-3

12 years

c. Zn-71

2.4 minutes

d. Rb-85

This is a stable isotope. It does not decomposes.

Comparing the half lives, the isotope with the longest half life is Hydrogen - 3. With half life of 12 years.

Answer:

hex-1-ene with a hydroboration-oxidation reaction

Explanation:

In this case, we can start with the structure of 1-hexanol. In this alcohol, the "OH" is on the first carbon. Thus, the alkene that this alcohol can produce must have a double bond between carbons 1 and 2, that is, hex-1-ene.

Now, it is important to know which of the reactions we can use, hydroboration-oxidation, or oxymercuration-reduction. To decide which reaction to using, we must look again at the alcohol we want to produce. In this alcohol, the "OH" is attached to a primary carbon. Therefore, the addition of the "OH" must be made on the least substituted carbon, that is, carbon number 1.

Because of this, an anti-Markovnikov reaction (a reaction in which the "OH" is added on the less substituted carbon) must be used. The reaction, which serves us then is: hydroboration-oxidation since this reaction is anti-markovnikov.

See figure 1

I hope it helps!

Answer:

1.86 m

Explanation:

Step 1: Calculate the mass of solute and solvent in 100 grams of solution

We have a 15.0% by mass solution of MgCl₂ (solute) in H₂O (water). In 100 g of solution, there are 15.0 g of solute and 100.0 g - 15.0 g = 85.0 g of solvent.

Step 2: Calculate the moles corresponding to 15.0 g of MgCl₂

The molar mass of MgCl₂ is 95.21 g/mol.

[tex]15.0g \times \frac{1mol}{95.21 g} = 0.158mol[/tex]

Step 3: Convert the mass of water to kilograms

We will use the relationship 1 kg = 1,000 g.

[tex]85.0g \times \frac{1kg}{1,000g} = 0.0850kg[/tex]

Step 4: Calculate the molality of the solution

[tex]m = \frac{0.158mol}{0.0850kg} = 1.86m[/tex]

The molality is 1.86 m.

Given:

Mass solution of MgCl₂ in H₂O= 15%

Density= 1.127g/mL

To find:

Molality=?

Let's solve this question step by step:

Step 1: Calculate the mass of solute and solvent in 100 grams of solution

As it is given that 15.0% by mass solution of MgCl₂ (solute) in H₂O (water).

In 100 g of solution, there are 15.0 g of solute and 100.0 g - 15.0 g = 85.0 g of solvent.

Step 2: Calculate the moles corresponding to 15.0 g of MgCl₂

The molar mass of MgCl₂ is 95.21 g/mol.

Number of moles is given mass divided by the molar mass.

[tex]\text{Number of moles}= \frac{15g}{95.21g/mol} =0.158mol[/tex]

Step 3: Convert the mass of water to kilograms.

As we know, 1 kg = 1,000 g.

[tex]=\frac{85}{1000} =0.085kg[/tex]

Step 4: Calculate the molality of the solution.

Molality is a measure of the number of moles of solute in a solution corresponding to 1 kg or 1000 g of solvent.

[tex]\text{Molality}=\frac{0.158\text{mol}}{0.085\tetx{kg}} =1.86 m[/tex]

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Answer:

milligram, centigram, decigram

Hope this answer correct :)

Answer:

C

Explanation:

hope it helps.

The question is incomplete. Here is the complete question.

Consider the selenium atom, Se, and the bromine atom, Br.

Write out the full electron configuration fro each atom.

Se:

Br:

Calculate the Effective Nuclear Charge for each atom. Show all of your work for full credit.

Se:

Br:

Which atom is larger?

Answer and Explanation: Electron Configuration of an atom demonstrates the shape and energy of its electrons. One of the rules used for it is given by using Madelung's Rule, in which the order of increased energy of the electrons is:

1s < 2s < 2p < 3s < 3p < 4s < 4p < 5s < 6s < 4f < 5d < 6p < 7s < 5f < 6d < 7p

Atom of Selenium (Se) has 34 electrons. Its electron configuration is

Se: [tex]1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{4}[/tex]

Atom of Bromine has 35 electrons. Its electron configuration is

Br: [tex]1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{5}[/tex]

Effective Nuclear Charge ([tex]Z_{eff}[/tex])is the net positive charge experienced by an electron in a multi-electron atom. In other words, it is the net force that helds nucleus and electrons together.

It is calculated by: [tex]Z_{eff}=Z-S[/tex]

where

Z is the atomic number, i.e., number of protons of the atom

S is the nonvalence electrons, i.e., the number of electrons between the nucleus and the electron in question.

For Selenium (Se):

From the electron configuration, the valence shell is 4 with 6 valence electrons. Nonvalence electrons is the difference between valence and total electrons:

S = 34 - 6 = 28

[tex]Z_{eff}=34-28[/tex] = 6

The Effective Nuclear Charge of Se is 6

For Bromine (Br):

The valence shell, according to the configuration, is 4 and valence electrons are 7.

S = 35 - 7 = 28

[tex]Z_{eff}=35-28[/tex] = 7

The Effective Nuclear Charge fo Br is 7.

Bromine is larger than Selenium because it has bigger Effective Nuclear Charge, which means it held its electrons more loosely and, consequently, has a larger atomic radius.

Answer:

Traces of sodium impurity

Explanation:

Metal ions are identified by a characteristic colour imparted to flame by the metal ion solution. Various metals have various colours which they impart to a flame.

The energy of a flame is not sufficient for the excitation of electrons of Mg to a higher energy level. As a result of this, Mg do not give any color in Bunsen flame.

However, a few tinges of yellow-orange colour which is characteristic of sodium metal do appear when magnesium ions are exposed to a flame as a consequence of traces of sodium impurity in the magnesium ion solution.

Answer:

It's 10 cenimeters per second

Answer:

3.

Explanation:

Hello,

In this case, considering the given number:

[tex]2.30x10^5[/tex]

We can see that it does not have zeros to left of the first nonzero digit which is 2, therefore, we just have to consider the 2, 3 and 0 as significant figures because the right-handed zeros are actually considered. Hence, such measurement has 3 significant figures.

Answer:

Below

Explanation:

The coefficients in a chemical reaction are called stochiometric coefficients

they represent the number of atoms or molecules they are multiplied to.

A chemical reaction has generally this form:

Answer:

Products to reactants

Answer:

\large \boxed{\text{150 g TiCl}_{4}}  

Explanation:

We will need a balanced chemical equation with masses and molar masses, so, let's gather all the information in one place.

Mᵣ:     189.68                  79.87

           TiCl₄ + 2H₂O ⟶ TiO₂ + 4HCl

m/g:                                 50.0

To solve this stoichiometry problem, you must

1. Theoretical yield of TiO₂

[tex]\text{Theoretical yield} = \text{50.0 g actual} \times \dfrac{\text{100 g theoretical}}{\text{78.9 g actual}} = \text{63.37 g theoretical}[/tex]

2.  Moles of TiO₂

[tex]\text{Mass of TiO}_{2} = \text{63.37 g TiO}_{2} \times \dfrac{\text{1 mol TiO}_{2}}{\text{79.87 g TiO}_{2} } = \text{0.7934 mol TiO}_{2}[/tex]

3,  Moles of TiCl₄

The molar ratio is 1 mol TiO₂:1 mol TiCl₄.

[tex]\text{Moles of TiCl}_{4} = \text{0.7934 mol TiO}_{2} \times \dfrac{\text{1 mol TiCl}_{4}}{\text{1 mol TiO}_{2}} = \text{0.7934 mol TiCl}_{4}[/tex]

4.  Mass of TiCl₄

[tex]\text{Mass of TiCl}_{4} = \text{0.7934 mol TiCl}_{4} \times \dfrac{\text{189.98 g TiCl}_{4}}{\text{1 mol TiCl}_{4}} =\textbf{150 g TiCl}_{\mathbf{4}} \\\\\text{You must use $\large \boxed{\textbf{150 g TiCl}_{\mathbf{4}}}$}[/tex]

Answer:

See explanation

Explanation:

Anode;

Sn(s) ------> Sn^2+(aq) + 2e

Cathode;

Mn^2+(aq) + 2e ------> Mn(s)

The minimum voltage required to drive the reaction is the cell voltage. The cell voltage is obtained from;

E°cell= E°cathode - E°anode

E°cell= -1.19 - (-0.14)

E°cell= -1.05 V

Volume ..........is the answer

Answer:

The formula of the first compound is RQ

Explanation:

Chemical formula is the simplest whole number ratio of moles of each element in the compound.

To determine the formula of a compound we must know the molar mass of each element (How many grams weighs a mole of the compound).

The formula of the second compound is RQ₃. That is 1 mole of R and 3 moles of Q.

1 mole of R weighs 7.00g. That means its molar mass is 7g/mol.

3 moles of Q weighs 4.50g. Its molar mass is 4.50g / 3 moles: 1.50g/mol

In the first compound, there are 14.0g = 2 moles of R

And 3.00g of Q = 2 moles of Q.

And you can think formula is:

R₂Q₂

But, as formula is the simplest whole number ratio,

Answer:

D. The side chains of D-Arg and D-Lys are not positioned to bind correctly at the active site

Explanation:

Stereospecificity is the ability to distinguish between stereoisomers of of a particular compound. L- and D- structures of compounds in living organisms are usually present in only one form due to stereospecificity. For example, naturally occuring amino acids in proteins are usually present as L-isomers.

Since enzyme are proteins, their active sites are composed of L-amino acid and they show stereospecificity in the reactions they catalyze. In their binding sites, only substrates complementary in structure can bind in order for catalysis to proceed. Therefore, only amino acids in the L- configuration are complementary to the active site of enzymes.

In the case of serine proteases, The side chains of -Arg and D-Lys will not be positioned properly for binding at the binding site of serine proteases, therefore, no catalysis will occur. On the other hand, L-Arg and L-Lys can bind to the catalytic site of serine proteases since they are complementary fits to the active site of the enzymes.

Answer:

[tex]\%m=0.15\%[/tex]

Explanation:

Hello,

In this case, we are asked to compute the by mass percent representing the toxicity of ethylene glycol in the body mass. In such a way, since the by mass percent is computed with the shown below formula:

[tex]\%m=\frac{m_{ethylene \ glycol}}{m_{ethylene \ glycol}+m_{body\ mass}}*100\%[/tex]

We can use the given masses to obtain:

[tex]\%m=\frac{1.5g}{1.5g+1000g}*100\%\\ \\\%m=0.15\%[/tex]

Best regards.

Answer:

a) 7.94 x 10²³ molecules, b) 5.62 g SO2, c) 1.97 L

Explanation:

a) We need to first convert Cu2S to moles. Since molar mass of Cu2S is 159.14 g/mol, 14.0 g = 0.0880 mol. Using molar ratios (3 mol O2/2 mol Cu2S, 0.0880 mol of Cu2S = 0.132 mol O2. Since 1 mol contains 6.02 x 10²³ molecules, 0.132 mol O2 = 7.94 x 10²² molecules O2.

b) Since the molar ratios of Cu2S to SO2 is 1:1, 0.0880 mol of Cu2S produces 0.0880 mol SO2. To convert mol to grams, we use the molar mass of SO2 (64.06 g/mol) to figure out that 0.0880 mol SO2 = 5.63 g SO2.

c) At STP, 1 mol occupies 22.4 liters. 0.0880 mol SO2 x 22.4 L/1 mol = 1.97 L

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Answer:

(CH3)3CCHO

Explanation:

Carbonyl compounds that contain alpha hydrogen atoms are the only ones that can undergo aldol condensation reaction.

Aldol condensation is one of the condensation reactions in organic chemistry that occurs when an enol or an enolate ion reacts with another carbonyl compound to yield a β-hydroxyaldehyde or β-hydroxyketone, this is immediately followed by the dehydration of the product to yield a conjugated enone.

(CH3)3CCHO lacks alpha hydrogen atoms hence it does not undergo the aldol condensation.

Answer:

B

Explanation:

Answer: The mole fraction of benzene will be 0.34 and mole fraction of toluene is 0.66

Explanation:

According to Raoult's law, the vapor pressure of a component at a given temperature is equal to the mole fraction of that component multiplied by the vapor pressure of that component in the pure state.

[tex]p_1=x_1p_1^0[/tex] and [tex]p_2=x_2P_2^0[/tex]

where, x = mole fraction in solution

[tex]p^0[/tex] = pressure in the pure state

According to Dalton's law, the total pressure is the sum of individual pressures.

[tex]p_{total}=p_1+p_2\\[/tex][tex]p_{total}=x_{benzene}p_{benzene}^0+x_{toluene}P_{toluene}^0[/tex]

[tex]x_{benzene}=x[/tex],

[tex]x_{toluene}=1-x_{benzene}=1-x[/tex],

[tex]p_{benzene}^0=75torr[/tex]

[tex]p_{toluene}^0=22torr[/tex]

[tex]p_{total}=40torr[/tex]

[tex]40=x\times 75+(1-x)\times 22[/tex]

[tex]x=0.34[/tex]

Thus (1-x0 = (1-0.34)=0.66

Thus the mole fraction of benzene will be 0.34 and that of toluene is 0.66

Answer:

a. See figure 1

b. See figure 2

c. Three cycles

d. Four Acetyl-CoAs

Explanation:

a. Draw the condensed structural formula for the activated form of caprylic acid

For the activation of the fatty acid, an ATP molecule is needed to bind AMP in the acid group and then an Acetyl-CoA molecule to generate the activated fatty acid. (See figure 1)

b. Indicate the α- & β-carbon atoms in caprylic acid

By definition, the alpha and beta carbons are the carbons that are in positions 2 and 3 respectively to the main carbon. In this case, the main carbon is the carbon from the acid group, therefore the alpha carbon will be carbon 2 (red arrow) and the beta carbon will be carbon 3 (blue arrow). (See figure 2).

c. State the number of β-oxidation cycles for the complete oxidation of caprylic acid.

To calculate the cycles we have to use the equation:

[tex]Number~of~cycles:\frac{n}{2}-1[/tex], where n is the amount of carbons, in this case, we have 8 carbons, so:

[tex]Number~of~cycles:\frac{8}{2}-1=3[/tex]

We will have 3 cycles. (See figure 3)

d. State the number of acetyl-CoAs from the complete oxidation of caprylic acid

In the β-oxidation metabolic cycle, we have a relationship between Acetyl-CoA produced and the number of carbons:

[tex]Number~of~Acetyl~Coas:\frac{n}{2}[/tex] if n=8 we will have:

[tex]Number~of~Acetyl~Coas:\frac{8}{2}=4~Acetyl~Coas[/tex]

We will have 4 Acetyl-CoAs.

I hope it helps!

Answer: option (a) is the correct answer

Explanation:

The complete questions says;

You observe an exothermic gaseous reaction that is not spontaneous in forward direction at 1 atm and 298K. Which of the following statements about this reaction is true? a. This reaction will become spontaneous in forward direction at some temperature below 298K. b. This reaction will be spontaneous in forward direction at a higher pressure at 298K. c. This reaction will become spontaneous in forward direction at some temperature above 298K. d. This reaction is never spontaneous. e. The reverse reaction is always spontaneous.

The Answer:

(a). This reaction will become spontaneous in forward direction at some temperature below 298K

Explanation: First of all, we can acknowledge that the reaction seen here is an exothermic one, i.e energy is released in the process outwardly and as a result temperature is reduced during this process of energy loss.

Having understood that scenario, say we reduce it's temperature by ourself than forward reaction favors and after reaching at particular temperature, therefore we can confirm this to be a spontaneous reaction.

Let us use this to confirm what we have been saying.

Given;

ΔG = ΔH - TΔS

here ΔH is negative

it is non spontaneous, which means ΔG is positive so we continuously decraeses it's temperature than at a particular temperature.

The Entropy change becomes positive and reaction becomes spontaneous and ΔG become negative.

cheers i hope this helped !!

Answer:

The percentage of ethylene glycol that is fatal is 0.15 %

Explanation:

If the toxic quantity of ethylene glycol in a 1kg or 1000 g body weight is 1.5 g then the percentage of ethylene glycol that is fatal is

[tex]\frac{1.5}{1000}[/tex] ˣ 100 = 0.15%

Hence, the percentage of ethylene glycol that is toxic for any body weight is 0.15%. This percentage is very important in various aspects of science including drug discovery and food production/processing