Isotope Atomic Mass (amu) Percent Abundance
Silicon-28 27.98 92.21%

Silicon-29 28.98 4.70%

Silicon-30 29.97 3.09%
Look at the information given and predict whether the average atomic mass would be closer to Si-28, Si-29, or Si-30. Give reasons for your answer.

Answer:

Of the main group elements, fluorine has the highest electronegativity (EN = 4.0) and cesium the lowest (EN = 0.79). This indicates that fluorine has a high tendency to gain electrons from other elements with lower electronegativities.

Explanation:

Answer:

The percent yield would be 73%

Explanation:

The balanced reaction for the obtention of acetylsalicylic acid (aspirin) is the following:

Salicylic acid + acetic anhydride → acetylsalicylic acid + acetic acid

C₇H₆O₃          +          C₄H₆O₃        →         C₉H₈O₄           +    C₂H₄O₂

According to the reaction, 1 mol of salicylic acid reacts with 1 mol of acetic anhydride to give 1 mol of acetylsalicylic acid (aspirin) and 1 mol of acetic acid.

1 mol aspirin (C₉H₈O₄) = (9 x 12 g/mol) + (8 x 1 g/mol) + (4 x 16 g/mol)

                                     = 180 g

1 mol salicylic acid (C₇H₆O₃) = (7 x 12 g/mol) + (6 x 1 g/mol) + (3 x 16 g/mol)

                                              = 138 g

1 mol acetic anhydride (C₄H₆O₃) = (4 x 12 g/mol) + (6 x 1 g/mol) + (3 x 16 g/mol)

                                                      = 102 g

The stoichiometric ratio is = 138 g salicylic acid/102 g acetic anhydride= 1.35

We have:

2.0 g salicylic acid

acetic anhydride = 5.0 mL x 1.08 g/mL = 5.4 g

The reactants ratio is = 2.0 g salicylic acid/5.4 g acetic anhydride = 0.37

0.37 < 1.35 , therefore salicylic acid is the limiting reactant.

Now, we use the amount of salicylic acid to calculate the theoretical amount of aspirin. For this, we know that 1 mol of aspirin (180 g) is obtained from 1 mol of salycilic acid (138 g):

theoretical yield= 180 g aspirin/138 g salycilic acid x 2.0 g salycilic acid = 2.61 g aspirin

actual yield = 1.9 g

Finally, we calculate the yield:

percent yield = actual yield/theoretical yield x 100

        = 1.9 g/2.6 g x 100 = 72.8% ≅ 73%

Answer:

H3PO4 + 3NaOH ==> Na3PO4 + 3H2O

The balanced equation for the given reaction is [tex]3NaOH+H_3PO_4---- > Na_3PO_4+3H_2O[/tex]

A chemical reaction in which an acid and a base react quantitatively with each other is known as neutralization.

In a water reaction, neutralization means that there is no excess of hydrogen or hydroxide ions in the solution.

A neutralization reaction occurs when an acid and a base react to form water and a salt through the combination of H+ ions and OH- ions. The pH of neutralization of a strong acid and a strong base is 7.

Three moles of sodium hydroxide are required for one mole of phosphoric acid. The balanced equation tells us the following: 1 mol of H3PO4 reacts with 3 mol of NaOH.

It can be written as

[tex]3NaOH+H_3PO_4---- > Na_3PO_4+3H_2O[/tex]

Thus, this is the balanced equation for the given neutralizing reaction.

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Answer:

4

Explanation:

The Balmer series refers to a series of spectral emission lines of the hydrogen atom arising from electronic transitions from any higher level and terminating at the the energy level n= 2.

Using the relation;

1/λ = 1.09737*10^7 (1/2^2 -1/n^2initial)

We now have;

1/486 *10^-9 = 1.09737*10^7 (1/2^2 -1/n^2initial)

0.1875 = 1/2^2 -1/n^2initial

1/n^2initial = 1/2^2 - 0.1875

1/n^2initial = 0.0625

n^2initial = 16

ninitial = 4

Factors that affect the strength of electromagnets are the nature of the core material, strength of the current passing through the core, the number of turns of wire on the core and the shape and size of the core.

Answer:

an effect could be that the battery could be running out of juice or that there isnt enough wire on a nail on the electromagnet.

Explanation:

Answer:

The correct answer is 0.020 atm.

Explanation:

Partial pressure is calculated by using the formula,

Partial pressure = Mole fraction × Total pressure

The partial pressure of oxygen in a mixture can be calculated by using the formula,  

Mole fraction of oxygen in mixture = Number of moles of oxygen / No. of moles of oxygen + No. of moles of Helium

(1 gg or gigagram is equal to 10⁹ grams)

= 2 × 10⁹/32 /2 × 10⁹/32 + 98 × 10⁹ / 4

= 2.54 × 10⁻³

Now the partial pressure of oxygen = Mole fraction of oxygen × Total pressure of oxygen

= 2.54 × 10⁻³ × 8.0 atm

= 0.02032 atm

= 0.020 atm

Answer:

C The atoms has a tiny, massive nucleus at its center with electrons surrounding it

Explanation:

From the experiment by Rutherford, he suggested a model of the atom where there is a tiny but massive nucleus at the center with electrons surrounding it.

Answer:

A

Explanation:

Based on the arrows, the direction the air masses are moving is from west

to east.

These contains large volume of air which has a uniform temperature and

humidity. Air masses move in the atmosphere through the process known

as Convection.

The movement of the air tells us that the movement is from  the Western

part to the Eastern part of the atmosphere.

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Answer:

If you're talking about Solid, Liquid, and Gas the answer would be... well I'm not gonna give this to you straiight away but, here's a game! It has at least 5 letters in it...It has the letter I in it, It has a S in it Hope you got the answer! ✨Brainliest pwease!

Answer:

The reaction is 2F_2 (g) + 2H_2 O (g) rightarrow 4HF (g) + O_2 (g) 2 moles of fluorine gas (F_2) reacts with 2 moles of water vapors (H_2 O) to produce 4 moles of hy

Answer:

Creativity leads scientists to design new methods to test their hypotheses.

Creativity permits scientists to think of new questions to investigate.

Explanation:

A scientist must be very creative and must be a critical thinker.

Creativity is the ability of someone to use imaginations to solve a problem.

Answer:

B and D

Explanation:

Answer:

The emmision of ionizing radiation or particles caused by the spontaneous disintegration of atomic nuclei

or

the giving off of rays of energy or particles by the breaking apart of atoms of certain elements

Given :

A seawater sample contains 2.7 mg chlorophyll m⁻³.

To Find :

What is the chlorophyll concentration in units of mg L⁻¹.

Solution :

We know, 1 m³ = 1000 L .

So, 1 m⁻³ = 10⁻³ L⁻¹

Concentration is :

[tex]c = 2.7\ mg\ m^{-3}\\\\c = 2.7\times 10^{-3}\times \ mg\ L^{-1}\\\\c = 0.0027 \ mg\ L^{-1}\\\\c = 2.7\ \mu g \ L^{-1}[/tex]

Therefore, the chlorophyll concentration in units of mg L⁻¹ is [tex]2.7\ \mu g \ L^{-1}[/tex].

Hence, this is the required solution.

Answer:

1.45 Atmospheres = 146.92125 Kilopascals, or about 146.9 Kilopascals

Explanation:

1 Atmosphere = 101.325 Kilopascals, so 101.325 Kilopascals x 1.45 Atmospheres = 146.92125 Kilopascals.

Using the conversion table, the pressure of the compressed gas at 1.45 atm when converted to kilopascal becomes 146.92 kPa.

Atm is the standard atmosphere which is a unit of pressure.

From conversion table

1 atm atmospheric pressure is equivalent to 101.325 kPa ( kilopascal ).

Now, the pressure of the compressed gas at 1.45 atm will be;

P = 1.45 × 101.325 kPa

P = 146.92 kPa

Therefore, the pressure of the compressed gas at 1.45 atm when converted to kilopascal using the conversion table becomes 146.92 kPa.

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Answer:

The answer is "[tex]\bold{1.39 \ mg}[/tex]".

Explanation:

Please find the complete question in the attached file.

Total Moles of [tex]Mg_2^{+}[/tex] = moles of [tex]MgSO_4[/tex]

                                 [tex]= \frac{mass}{molar \ mass \ of MgSO_4}\\\\= \frac{0.450}{120.37}\\\\ = 0.0037385 \ mol[/tex]

[tex]Mg_2^{+} + EDTA4^{-} \longrightarrow Mg(EDTA)2^{-}[/tex]

EDTA mol in 37.6 mL of solution = 50.0 mL of [tex]Mg2^{+}[/tex]

                                                      [tex]= \frac{50.0}{500} \times[/tex] total moles of [tex]Mg2^{+}[/tex]

                                                      [tex]= \frac{50.0}{500} \times 0.0037385\\\\= 3.7385 \times 10^{(-4)} \ mol\\[/tex]

[tex]Ca2^{+} + EDTA4^{-} \longrightarrow Ca(EDTA)2^{-}[/tex]

[tex]CaCO_3 Moles = Ca2^{+} Moles =[/tex] EDTA moles in a solution of 1.40 mL

                      [tex]= \frac{1.40}{37.6} \times 37.6 \ mL[/tex] the solution of EDTA moles.

                      [tex]= \frac{1.40}{37.6} \times 3.7385 \times 10^{(-4)} \\\\= 1.392 \times 10^{(-5)}\ mol\\\\[/tex]

Mass of [tex]CaCO_3 =[/tex]mole[tex]\times[/tex] the molar mass of [tex]CaCO_3[/tex]

                            [tex]= 1.392 \times 10^{(-5)} \times 100.09\\\\= 0.00139 \ g\\\\ = 1.39 \ mg[/tex]

Answer:

D. when the number of moles of acid is exactly equal to the number of moles of base.

Explanation:

Regarding options A. and E., pKa and pKb would only be taken into consideration if the titrations were of weak acids and bases. However it is possible to have a titration of monoprotic acids and bases with strong acids and bases.

Another way of looking at the answer is identifying which one best describes the equivalence point.

Answer:

z = 2s

Explanation:

This is the only info given.

Answer:

Sodium hydroxide reacts with iron(III) chloride to produce iron(III) hydroxide and sodium chloride.

Hope this helps plz hit the crown :D

Answer:

4,2,3,1

Explanation:

Answer:

V₂ = 22.84 L

Explanation:

Given data:

Initial volume = 20.0 L

Initial pressure = 1.50 atm

Initial temperature = 23 °C (23 +273 = 296 K)

Final temperature = 271°C (271+273 = 544 K)

Final pressure = 3.50 atm

Final volume = ?

Formula:  

P₁V₁/T₁ = P₂V₂/T₂  

P₁ = Initial pressure

V₁ = Initial volume

T₁ = Initial temperature

P₂ = Final pressure

V₂ = Final volume

T₂ = Final temperature

Solution:

V₂ = P₁V₁ T₂/ T₁ P₂  

V₂ = 1.50 atm × 29.0L ×544 K / 296 K × 3.50 atm

V₂ = 23664 atm .L. K / 1036 atm.K

V₂ = 22.84 L

Answer:

C.

Explanation:

They will need to know the influence of gravitational force on objects because gravity can affect an objects weight.

Answer:

i don't understand the question

Explanation:

Answer:

The cell potential = +0.03 V

Explanation:

The half reactions for the cells are given below:

Oxidation half reaction (anode):   Zn(s) ----> Zn²⁺(aq) + 2e⁻

Reduction half reaction (cathode):  Zn²⁺(aq) + 2e⁻ -----> Zn(s)

To calculate cell potential of the cell, we use the equation given by Nernst, which is given as: Ecell = E°cell - (0.0591/n) log Q

where  Q = Concentration of dilute solution/Concentration of concentrated solution = 0.01/0.1

n = number of moles of electrons transferred = 2

Since, the cell is a concentration cell, E°cell = 0

therefore, the Nernst equation becomes, Ecell = - (0.0591/n) log Q

substituting the values;

Ecell = - (0.0591/2) log (0.01/0.10)

Ecell = +0.03 V

Therefore, the cell potential = +0.03 V

Answer:

Explanation:

1) Pure substance: Water (found at home)

Appearance: It is homogeneous since it is a single substance that appears as liquid. Homogeneous is when the components of a substance are in a single phase

Separating technique: It's component cannot be separated by physical means

Boiling point: Water boils at 100 °C

Melting point: Water melts/freezes at 0°C

2) Pure substance: Table salt (found at home)

Appearance: It is also homogeneous as it is a single substance that is solid. Separating technique: It's component cannot be separated by physical means

Boiling point: Water boils at 1,465 °C

Melting point: Water melts/freezes at 801 °C

3) Pure substance: Butter (found at home and grocery store)

Appearance: It is homogeneous even though it contains different components

Separating technique: It's component can be separated by physical means since butter is an emulsion of fat in water. The 15% water content can be evaporated/distilled out at 100 °C

Boiling point: Butter starts boiling at about 110-120 °C

Melting point: It melts at about 37 °C

4) Pure substance: Candle (wax) (found at home and grocery store)

Appearance: It is homogeneous

Separating technique: It's component cannot be separated by physical means

Boiling point: It starts boiling around 370 °C

Melting point: It melts at about 37 °C

5) Pure substance: table sugar/sucrose (found at home, grocery stores and in supermarkets)

Appearance: It is homogeneous

Separating technique: It's component cannot be separated by physical means

Boiling point: It starts boiling around 697 °C

Melting point: It melts at about 186 °C

A pure substance is an homogeneous material, having a composition, and

properties that are consistent through out the material.

The chemical properties of a pure substance are defined, such as the

products of its reaction can be predictable.

A chemical is pure when it consist of a single type of particle such as an

element, a molecule or a compound.

The five pure substances are presented as follows;

[tex]\displaystyle\begin{tabular}{|l|l|l|l|l|}\underline{Pure \ Substances}&\underline{Appearance}&\underline{Separaing Tech}&\underline{Boiling \ Point}&\underline{Melting \ point}\\1. Diamond&Translucent \ solid&Inseparable&3550^{\circ}&4830^{\circ}\\2. Table \ salt&White\ crystals&Insepble&801^{\circ}&1413^{\circ}\\3. Water&Tran parent \ liquid&Insepble&0^{\circ}&100^{\circ}\\4. Sugar&Whilte \ crystals&Heating&Decomposes&186^{\circ}\\5. Gold&Yellowish \ metal&Inseparable& 2700^{\circ}&1064^{\circ}\end{array}[/tex]

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Answer: 51.9961 g/mol, don't know if it helps :)

Explanation:

Answer:

Chromium is a steel-gray, lustrous, hard metal that takes a high polish, is fusible with difficulty, and is resistant to corrosion and tarnishing.

The most common oxidation states of chromium are +2, +3, and +6, with +3 being the most stable. +4 and +5 are relatively rare. Chromium compounds of oxidation state 6 are powerful oxidants.ion:

Answer:

34672.96 s

Explanation:

m = Mass of copper = 6.32 g

M = Molar mass of copper = 63.5 g/mol

F = Faraday constant = 96500 C/mol

The electrode equation would be

[tex]Cu^{2+}(aq)+2e^{-}=Cu(s)[/tex]

Number of electrons = 2 = e

I = Current = 0.554 A

t = Time taken

Charge would be

[tex]Q=\dfrac{m}{M}eF\\\RightarrowQ=\dfrac{6.32}{63.5}\times 2\times 96500\\\Rightarrow Q=19208.82\ \text{C}[/tex]

Charge is given by

[tex]Q=It\\\Rightarrow t=\dfrac{Q}{I}\\\Rightarrow t=\dfrac{19208.82}{0.554}\\\Rightarrow t=34672.96\ \text{s}[/tex]

Time taken to deposit the copper is 34672.96 s.

Answer:

5.74 L O₂

General Formulas and Concepts:

Chemistry - Gas Laws

Explanation:

Step 1: Define

RxN:   2HgO (s) → 2Hg (s) + O₂ (g)

Given:   111 g HgO

Step 2: Identify Conversions

STP

Molar Mass of Hg - 200.59 g/mol

Molar Mass of O - 16.00 g/mol

Molar Mass of HgO - 200.59 + 16.00 = 216.59 g/mol

Step 3: Stoichiometry

[tex]111 \ g \ HgO(\frac{1 \ mol \ HgO}{216.59 \ g \ HgO} )(\frac{1 \ mol \ O_2}{2 \ mol \ HgO} )(\frac{22.4 \ L \ O_2}{1 \ mol \ O_2} )[/tex] = 5.73988 L O₂

Step 4: Check

We are given 3 sig figs. Follow sig fig rules and round.

5.73988 L O₂ ≈ 5.74 L O₂

Answer:

Mega = 10^6

Milli = 10^-3

Explanation:

Mega is whatever times 10 to 6th power.

Milli is whatever times 10 to the -3rd power.

Answer:

a) When air inside the tires gets colder, it shrinks, so the tires seem flat, even though they haven't lost any air.

b) When the air inside the soda can gets hot, the molecules of gas move faster, exerting more and more and more pressure, eventually exploding the soda can.

c) When the nalgene is cooled, the air pressure inside will lower; the volume of the nalgene will stay the same, though, because the nalgene is a rigid container.

Answer:

1+1=2 Unless this is a trick question. Then it's most likely 11.

Explanation:

1 + 1 = 2

thxs for the points realy tho thxs