3. Scientific methods may include three steps of study as listed below. Explain each step in detail with a complete content related sentence. (ref: p.12-16) a. Hypothesis b. Theory c. Scientific law

Answer : The correct answer is 1.46

Explanation :

The following rules are used to round off a number to the required number of significant figures:

(1) If the rightmost digit to be removed is more than 5, the preceding number is increased by one.

(2) If the rightmost digit to be removed is less than 5, the preceding number is not changed.

(3) If the rightmost digit to be removed is 5, then the preceding number is not changed if it is an even number but it is increased by one if it is an odd number.

(4) The same procedure is follow for decimal values.

As we are given, 1.4593

In the given answer, there are 5 significant figures. Now we have to convert it into 3 significant figures.

According to the rules, round off the given measurement in three significant figures as 1.46

Therefore, the correct answer is 1.46

Answer:

The simplest chemical formula of the compound is Cu(C₆H₁₁O₇)₂

Explanation:

Given mass of sample = 1.4 g

mass of copper in the sample = 0.2 g

mass of the gluconate =1.4 - 0.2 = 1.2 g

The mole ratio is determined first using the formula;

mole ratio = reacting mass / atomic mass

atomic mass of copper = 63.55

mass of gluconate, C₆H₁₁O₇ = 12*6 + 1*11 + 16*7 = 195 g/mol

mole ratio ( copper : gluconate) = 0.2/63.55 : 1.4/195

mole ratio ( copper : gluconate) =  0.003 : 0.007

convert to whole number ratios by dividing with the smallest ratio

mole ratio ( copper : gluconate) = 0.003/0.003 : 0.007/0.003

mole ratio ( copper : gluconate) = 1 : 2

Therefore, the simplest chemical formula of the compound is Cu(C₆H₁₁O₇)₂

Answer:

answer is in exaplation

Explanation:

Answer. Chemical reaction had occurred and both the powders are different substances.

Explanation:

As density is an intensive property of the substance.Which means that different substance have different densities.

Density = \frac{mass}{volume}

volume

mass

Density of powder 1, d_1=\frac{0.5g}{45cm^3}=0.11g/cm^3d

1

=

45cm

3

0.5g

=0.11g/cm

3

Density of powder 2, d_2=\frac{1.3g}{65cm^3}=0.02g/cm^3d

2

=

65cm

3

1.3g

=0.02g/cm

3

On comparing both the densities of the powders we can say that both the substances are different. So we can conclude that the chemical reaction had occurred.

Answer:

A. the law of constant composition

Explanation:

The molecules in the container would have the same composition because they would have traded around atoms until an equilibrium was reached with every molecule having 1 Hydrogen and 1 Chlorine.

Answer:

Human action has affected the population in quite a negative way. Technological innovations and urbanization gave rise to a high degree of pollution on the land, air and water.

Emission of hydrocarbons from automobiles and factories are known to pollute and cause sicknesses related to the respiratory system thereby shortening the lifespan of humans. Pollution of water bodies also cause death of sea animals and thereby reducing food availability of humans.

Answer:

All except ch4

Explanation:

NH3 N H 3 and HF can form hydrogen bonds as they have a hydrogen atom bonded to fluorine and nitrogen atoms.

Hydrogen bonds are formed between hydrogen and a highly electronegative atom such as oxygen, halogens etc.  Among the given compounds HI form hydrogen bond.

Hydrogen bond a strong bond type formed between hydrogen and an electronegative atom. Water, hydrogen halides, hydrogen sulphide etc are formed by hydrogen bonds.

Hydrogen is an electropositive atom and will easily lose an electron to a electronegative atom. Thus hydrogen bonds with atoms by sharing electrons each other where, the shared pair of electrons are attractively pulled to the electronegative atom.

Therefore, all the hydrogen bonded compounds are polar in nature.  Hydrogen bonds are strong bonds and it can be seen in proteins, DNA, and in other biomolecules.

HI or hydrogen iodide forms hydrogen bond because iodine is comparatively electronegative.

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Answer:

Molarity: 0.111M

% (w/w): 0.666

Explanation:

The reaction of NaOH with acetic acid (CH₃COOH) is:

NaOH + CH₃COOH → CH₃COO⁻Na⁺ + H₂O

where 1 mole of NaOH reacts per mole of acetic acid producing 1 mole of water and 1 mole of sodium acetate.

As 39.26mL ≡ 0.03926L of 0.1062M are required to titrate the solution of acetic acid. Moles are:

0.03926L × (0.1062mol / L) = 4.169x10⁻³ moles of NaOH. As 1 mole of NaOH reacts per mole of acetic acid:

4.169x10⁻³ moles of CH₃COOH.

Molarity is defined as ratio between moles of substance and volume of solution in liters. Thus, molarity of acetic acid solution is:

4.169x10⁻³ moles of CH₃COOH / 0.03754L = 0.111M

As molar mass of acetic acid is 60g/mol, 4.169x10⁻³ moles weights:

4.169x10⁻³ moles × (60g / mol) = 0.2501 g of acetic acid

Now, assuming density of solution as 1.00g/mL, 37.54mL weights 37.54g.

Thus, percent by weight is:

0.2501g CH₃COOH / 37.54g × 100 = 0.666% (w/w)

The molarity of acetic acid is 0.11M and the percent by weight is 0.666%.

Molarity of any solution is used to define their concentration and it will be calculated as:

M = n/V, where

n = moles

V = volume

Molarity of acetic acid will be calculated as:

M₁V₁ = M₂V₂, where

M₁ = molarity of acetic acid = ?

V₁ = volume of acetic acid = 37.54mL = 0.037L

M₂ = molarity of NaOH = 0.1062M

V₂ = volume of NaOH = 39.26mL = 0.039L

On putting all these values on the above equation we can calculate the molarity as:

M₁ = (0.1062)(39.26) / (37.54) = 0.11M

Now we calculate the moles of acetic acid by using the molarity formula as:

n = 0.11M × 0.037L = 0.00407 moles

Molar mass of acetic acid = 60g/mole

Mass of 0.00407 moles of acetic acid = 4.1x10⁻³ moles×(60g / mol) = 0.2501 g

Density of solution = 1.00 g/mL

So, 37.54mL in 1g/mL = 37.54g/mL

Percent by weight will be calculated as:

%w/w = 0.2501g CH₃COOH / 37.54g × 100 = 0.666% (w/w)

Hence, molarity and %(w/w) of acetic acid is 0.11M and 0.666% respectively.

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Answer:

Gold(III) chloride

Answer:

[tex]M=0.0637M[/tex]

Explanation:

Hello,

In this case, the undergoing chemical reaction is:

[tex]Pb(NO_3)_2(aq)+2NaI(aq)\rightarrow PbI_2(s)+2NaNO_3(aq)[/tex]

Thus, for 0.904 g of precipitate, that is lead (II) iodide, we can compute the initial moles of lead (II) ions in lead (II) nitrate:

[tex]n_{Pb^{2+}}=0.904gPbI_2*\frac{1molPbI_2}{461gPbI_2}*\frac{1molPb(NO_3)_2}{1molPbI_2} *\frac{1molPb^{2+}}{1molPb(NO_3)_2} =1.96x10^{-3}molPb^{2+}[/tex]

Finally, the resulting molarity in 30.8 mL (0.0308 L):

[tex]M=\frac{1.96x10^{-3}molPb^{2+}}{0.0308L}\\ \\M=0.0637M[/tex]

Regards.

Answer:

The functional class(es) of this compound is(are):

Explanation:

3450 cm-1 is indicative of OH stretching

1725 cm-1 is indicative of carbonyl group C=O

1100cm-1 shows carbon is bonded to electronegative element e.g C-O

Further information on molecular formula is required for proper structural elucidation

Answer:

If you're ever shaving in the bathroom, turn the water off.

Explanation:

If you do this, you can save at least 3-4 pounds of water.

Answer:

The following activities can help conserve water while taking showers:

1) Lower shower time

2) Don't leave shower running.

3) Check for leaks

Answer:

Approximately [tex]21\; \rm g[/tex].

Explanation:

[tex]\rm H_2SO_4[/tex] (a diprotic acid) reacts with [tex]\rm NaOH[/tex] (a monoprotic base) at a one-to-two ratio:

[tex]\rm 2\; NaOH\, (s) + H_2SO_4\, (aq) \to Na_2SO_4\; (aq) + 2\; H_2O\, (l)[/tex].

In other words, if [tex]n(\mathrm{NaOH})[/tex] and [tex]n(\mathrm{H_2SO_4})[/tex] represent the number of moles of the two compounds reacted, then:

[tex]\displaystyle \frac{n(\mathrm{H_2SO_4})}{n(\mathrm{NaOH})} = \frac{1}{2}[/tex].

Look up the relative atomic mass data on a modern periodic table:

Calculate the (molar) formula mass of [tex]\rm H_2SO_4[/tex] and [tex]\rm NaOH[/tex]:

[tex]M(\mathrm{H_2SO_4}) = 2 \times 1.008 + 32.06 + 4 \times 15.999 = 98.072\; \rm g \cdot mol^{-1}[/tex].

[tex]M(\mathrm{NaOH}) = 22.990 + 15.999 + 1.008 = 39.997\; \rm g \cdot mol^{-1}[/tex].

Calculate the number of moles of formula units in that [tex]33.8\; \rm g[/tex] of [tex]\rm NaOH[/tex]:

[tex]\begin{aligned}n(\mathrm{NaOH}) &= \frac{m(\mathrm{NaOH})}{M(\mathrm{NaOH})} \\ &= \frac{33.8\; \rm g}{39.997\; \rm g \cdot mol^{-1}} \approx 0.845\; \rm mol\end{aligned}[/tex].

Apply the ratio [tex]\displaystyle \frac{n(\mathrm{H_2SO_4})}{n(\mathrm{NaOH})} = \frac{1}{2}[/tex] to find the (maximum) number of moles of [tex]\rm H_2SO_4[/tex] that would react with the [tex]33.8\; \rm g[/tex] of [tex]\rm NaOH[/tex]:

[tex]\begin{aligned}n(\mathrm{H_2SO_4}) &= \frac{n(\mathrm{H_2SO_4})}{n(\mathrm{NaOH})} \cdot n(\mathrm{NaOH})\\ &= \frac{1}{2} \times 0.845 \approx 0.4225\; \rm mol\end{aligned}[/tex].

Calculate the mass of that [tex]0.4225\; \rm mol[/tex] of [tex]\rm H_2SO_4[/tex]:

[tex]\begin{aligned}m(\mathrm{H_2SO_4}) &= n(\mathrm{H_2SO_4}) \cdot M(\mathrm{H_2SO_4})\\ &= 0.4225 \; \rm mol \times 98.072\; \rm g \cdot mol^{-1} \approx 41.435\; \rm g \end{aligned}[/tex].

When the maximum amount of [tex]\rm H_2SO_4[/tex] is reacted, the minimum would be in excess. Hence, the minimum mass of

[tex]62\; \rm g - 41.435\; \rm g \approx 21\; \rm g[/tex] (rounded to two significant figures.)

Answer:

3) 310 g/mol

Explanation:

Hello,

In this case, for calcium carbonate, we are able to compute its gram-formula mass by considering the atomic mass of each element composing it and their subscripts as shown below:

[tex]M=3*m_{Ca}+2*m_P+4*2*m_O\\[/tex]

Thus, we compute:

[tex]M=3*40g/mol+2*31g/mol+4*2*16g/mol\\\\M=310g/mol[/tex]

Hence answer is 3) 310 g/mol . Remember this is also known as the molar mass of the mentioned compound.

Best regards.

Answer:

409.0 kg of sodium sulfate decahydrate will produce 4.49×10⁵ kJ

of heat energy.

Explanation:

CHECK THE COMPLETE QUESTION BELOW

To make use of an ionic hydrate for storing solar energy, you place 409.0 kg of sodium sulfate decahydrate on your house roof. Assuming complete reaction and 100% efficiency of heat transfer, how much heat (in kJ) is released to your house at night? Note that sodium sulfate decahydrate will transfer 354 kJ/mol

EXPLANATION

Here we were asked to calculate the amount of heat will be generated by 409.0 kg of sodium sulfate decahydrate at night assuming there Isa complete reaction and 100% efficiency of heat transfer in the process

The molecular weight of sodium sulfate decahydrate (H₂₀Na₂O₁₄S) is needed here, so it must be firstly calculated.

The molecular weight of sodium sulfate decahydrate (H₂₀Na₂O₁₄S)

( 1*20) + (22.98*2) + (16*14)+ (32*14)= 322.186 g/mol.

Thus 409.0 kg of H₂₀Na₂O₁₄S will have a value which is equivalent to = (409000g)/(322.186 g/mol.)

=1269.453mol of H₂₀Na₂O₁₄S.

But it was stated in the the question that per mole of H₂₀Na₂O₁₄S will transfer 354 kJ heat.

Therefore, 1269.453mol will transfer 1269.453× 354 kJ = 4.49×10⁵ kJ of heat.

Hence, 409.0 kg of sodium sulfate decahydrate will produce

4.49×10⁵ kJ of heat energy.

Answer:

Explanation:

Step 1: NaCl(s) → Na(s) + 1/2 Cl2(g)  ΔHf   (ionization energy) in this step energy is required to change the phase of the compound

Step 2: Na(s) + 1/2 Cl2(g) → Na(g) + 1/2 Cl2(g)  ΔHa  (elements needed to be in gaseous state for born-haber cycle so metal changes from solid to gas state by changing the enthalpy.

Step 3: Na(g) + 1/2 Cl2(g) → Na(g) + Cl (g)  1/2ΔHd  

Step 4: Na(g) + Cl(g) → Na⁺(g) + Cl⁻(g)  IE+EA  ( in this step both ionization energy and electron affinity was involved because in metal (Na) electron is added which needs the energy and this energy draw from the step 3 and Chlorine require releasing electron to be in ionic state so when electron leaves the orbit energy releases.

Step 5: final step is Hess Law which is the combination of all the steps which step 4 again go back to step 5 and this cycle continues by repeating same steps    Na⁺(g) + Cl⁻(g)→NaCl(s)

at this step heat of formation is calculated

Heat of formation= atomization energy+ dissociation energy+ sum of ionization energies + sum of electron affinity + lattice energy.

2:  if we look at the electron configuration of the nitrogen it has 5 electrons in its outermost shell which indicates it can make 5 bonds 4 bonds and 1 lone pair usually and Oxygen has 6 electrons in its outermost shell. So nitrate ion have the total number of 24 electrons including the 1 electron which shows on the compound.

So when they make nitrate ion NO₃⁻¹ it shows that nitrate has 3 resonance structures. Nitrogen's three sigma bonds are attached to oxygen and fourth one make 1 pie bond which can rotate, delocalized and change its position anytime from one Oxygen atom to other oxygen atom.

Answer:

AT STOICHIOMETRIC POINT, THE VOLUME OF ACID ADDED IS 0.01 L

AT HALF-WAY POINT, THE VOLUME OF ACID IS 0.0050 L

Explanation:

In solving titration problems, you must remember this formula;

MaVa = MbVb

Since M a= 0.005 M

Mb = 0.010 M

Vb = 5 mL = 5 /1000 = 0.005 L

Va = unknown.

Solving for Va, we have:

Va = MbVb / Ma

Va = 0.010 * 0.005 / 0.005

Va = 0.01 L

So therefore, the volume of acid added at:

1. the stoichiometric point is 0.01 L

2. half-way point of titration is 0.01 /2 = 0.0050 L

For the pH:

Since HCl is a strong acid, it dissociate into {H30}+ ion.

First calculate the number of moles of hydronium ion

number of mole = concentration of hydronium ion {H30}+ * Volume

n = 0.005 * 0.01  = 0.00005 moles

A. At initial point of the titration, the volume of base added is 0 L

{H30]+ = n(H+)/ V = 0.00005 / 0.01 = 0.005 M

pH  = - log {0.005}

pH = 2.3

B. At the final point, since the volumes and concentrations of acid and base are the same, the pH is equal to 7.

n(H+) = n(OH^-)

pH = 7

Answer:

b) sp^2

Explanation:

Hybridization refers to the concept that atomic orbitals fuse to form newly hybridized orbitals, which in turn, influences molecular geometry and bonding properties. In chemistry, orbital hybridisation (or hybridization) is the implies the mixing of atomic orbitals to form hybrid orbitals (with different energies, shapes, etc., different from that of the component atomic orbitals) suitable for the pairing of electrons to form chemical bonds according to the principles of the valence bond theory.

In 1931 Linus Pauling proposed the idea of “mixing” the orbitals or “hybridizing” them to account for certain observed bonding patterns. Pauling proposed a sort of a combination of the orbitals giving you an orbital that has partial characters.

Hybridization is merely a mathematical construct. It is never an actual “process” that occurs within orbitals . Hybridization is a mathematical model that describes how the atomic orbitals would’ve looked like based on the observable molecular orbitals.

sp2 hybridization leads to the formation of a double bond. sigma bonds may also be formed depending on the valency of the central atom. In alkenes, an sp2 hybridized carbon atom forms a double bond in addition to two sigma bonds to other atoms.

The predicted hybridization is:

b) [tex]sp^2[/tex]

It is the integration of atomic orbitals to shape new orbitals with exclusive energies and shapes than the unique orbitals.

Given: An atom that's surrounded with the aid of using a double bond and unmarried bonds.

[tex]sp^2[/tex]  hybridization ends in the formation of a double bond. sigma bonds can also be shaped relying at the valency alkenes, an   [tex]sp^2[/tex]sigma bonds to different atoms.

Thus, correct option is b.

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Answer:I hope it will be beneficial for you

Force of attraction between the particles of solid is very strong the particles of solid are held together by strong inter molecular forces leading to the formation of a rigid structure

Force of attraction between the particles of the liquid is weak as compare to solids there particles are far away from each other and have the property to move easily.

Force of attraction between the particles of gases is very weak than the two states hence the particles of gases are highly compressible having week intermolecular interaction between them and have indefinite shape and volume

Answer:

Forces between particles in Liquids are closely packed  compared to other states of matter like the liquid and gaseous state of matter.

Explanation:

Answer: The result section of the project contains your findings while carrying out your research or study.

Explanation:

The Results section of a research or study usually contains only the findings of your study or research.The findings which usually include

1. Data presented in tables, charts, graphs, and other figures.

2. A contextual analysis of this data explaining its meanings. Usually in sentences.

Our result gotten is not discussed in result section because every project or research work has a discussion page where every results or findings are discussed. The result section is expected to carry what you found.

Answer: 8 (feet)

Explanation:

24 inches = 2 feet

48 inches = 4 feet

12 inches = 1 foot

To find volume you do Base * Width * Height

2*4*1 = 8

Hope this helps!

The correct answer is  8 (feet).

How to calculate ?

Therefore, 2*4*1 = 8

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Answer:

F⁻(aq) + H₂O(l) ⇄ HF(aq) + OH⁻(aq)

Explanation:

According to Brönsted-Lowry acid-base theory, an acid is a substance that donates H⁺ ions. In this sense, hydrofluoric acid is an acid according to the following equation.

HF(aq) + H₂O(l) ⇄ F⁻(aq) + H₃O⁺(aq)

According to Brönsted-Lowry acid-base theory, a base is a substance that accepts H⁺ ions. In this sense, the fluoride ion is a base according to the following equation.

F⁻(aq) + H₂O(l) ⇄ HF(aq) + OH⁻(aq)

The equilibrium constant for this reaction is Kb = 1.39 × 10⁻¹¹.

Answer:

301.8 g

Explanation:

We prepare a solution with 200.4 g of water (solvent) and 101.42 g of salt (solute). The mass of the solution is equal to the sum of the mass of the solvent and the mass of the solute.

m(solution) = m(solute) + m(solvent)

m(solution) = 200.4 g + 101.42 g

m(solution) = 301.8 g (we round-off to one decimal according to the significant figures rules)

Answer:

Some of the methods in Methods in electrochemistry that can be used for the separation of proteins and enzymes are as follows:

Redox transformations: In this method enzymes or proteins would be adsorbed on the electrode surface and facilitates direct electron transfer that causes denaturation and loss of their electrochemical activities and bioactivities. It is widely used in biosensors and biofuel cells.

Protein electrophoresis: In this process proteins are seperated by placing them in a gel matrix in the presence of an electrical field. In this method a negative charge is applied so that proteins move towards a positive charge.

Answer:

Ozone has dipole moments because its molecular chemical structure is no linear.

Explanation:

This molecular form refers to the geometry of said gas, which is potentially toxic and dangerous.

This non-linear geometric shape is what makes it have dipolarity.

Answer & explanation:

Summary on electrochemical cells and redox reactions:

Electrochemical cells (or batteries) can be defined as devices capable of transforming chemical energy into electrical energy through spontaneous reactions of redox, in which electron transfer occurs.

Redox it is a chemical reaction in which there is the occurrence of oxidation and reduction of atoms of substances (chemical species) present in the process.

Oxidation is the loss of electrons by an atom of a chemical species, while reduction is the gain of electrons by an atom of a chemical species.

Thus, during an oxirreduction reaction, electrons move from the species that loses them towards the species that will receive them. This "movement" results in the formation of an electric current (or electrical energy) as occurs with batteries, for example.

Answer:

pH = - log [concentration]

pH = - log (0.0043M)

pH = 2.37

Answer:

Part A

The natural abundance of Si-30 = 3.1

Part B

The mass of Si-30 = 29.9551 amu

Explanation:

Part A

The sum of the natural abundances = 100

Si-28 has a mass of 27.9769 amu and a natural abundance of 92.2%.

Si-29 has a mass of 28.9765 amu and a natural abundance of 4.67%

Si-30's mass and natural abundance are unknown.

Natural abundance for Si-30 = 100% - 92.2% - 4.67% = 3.13% = 3.1% to 2 s.f.

Part B

The total atomic mass of an element is an addition combination of the mass and natural abundances of all the isotopes of that element.

Molar mass of Silicon normally = 28.0855 amu

Let the mass of Si-30 be m

28.0855 = (27.9769×0.922) + (28.9765×0.0467) + (m×0.0313)

28.0855 = 27.14790435 + 0.0313m

0.0313m = 28.0855 - 27.14790435 = 0.93759565

m = (0.93759565/0.0313) = 29.9551325879 amu = 29.9551 amu

Hope this Helps!!

Part A:  The natural abundance of Si-30 = 3.1

  Lets solve the question:

Natural abundance (NA) refers to the abundance of isotopes of a chemical element as naturally found on a planet.

Natural abundance for Si-30 = [tex]100\% - 92.2\% - 4.67\% = 3.13\% = 3.1\%[/tex] in significant figures.

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Answer: From your question,

One could be exothermic which means that the final enthalpy will be less than the initial enthalpy. H= Hf-Hi(Hf<Hi).

In Endothermic reaction, the entropy is lowered by absorbing energy in the surronding. By so doing, the surronding losses energy and the reaction is not spontaneous.

H is positive and S (entropy) is positive.

Explanation:

Exothermic reaction is the reaction where heat is released In the surronding which lead to increase in the surronding Temperature.

Endothermic reaction is the reaction that absorb heat from the surronding and decrease the surronding Temperature.

Answer:

D

Explanation:

gr. 2.3 at 25°C; valence +3. Boron is a nonmetallic element existing as a dark brown to black amorphous powder or as an extremely hard, usually jet-black to silver-gray, brittle, lustrous, metallike crystalline solid

it is a network solid, a lattice of many covalent bonds (like diamond, except that it is black rather than transparent).

Network solid kind of solid is crystalline boron (B). Hence, option D is correct.

A network solid is a solid where all the atoms are covalently bonded in a continuous network.

Boron is a nonmetallic element existing as a dark brown to black amorphous powder or as an extremely hard, usually jet-black to silver-grey, brittle, lustrous, metallike crystalline solid

It is a network solid, a lattice of many covalent bonds (like a diamond, except that it is black rather than transparent).

Hence, option D is correct.

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