How many atoms are in 1.4 mol of phosphorus trifluoride (PF3)?

Answer:

geruow0irghvn3p0unhie0ghik

Explanation:

Answer:

c. 131 kPa

Explanation:

Hello!

In this case, since the relationship between volume and pressure is inversely proportional, based on the Boyle's law:

[tex]P_1V_1=P_2V_2[/tex]

Considering that the standard pressure is 101.325 kPa, we can compute the final pressure as shown below:

[tex]P_2=\frac{P_1V_1}{V_2}=\frac{620mL*101.325kPa}{480mL}\\\\P_2=131kPa[/tex]

Therefore, the answer is c. 131 kPa .

Best regards!!

Answer:

The answer is "4.37."

Explanation:

at [tex]0^{\circ} C\ Ka = 1.76 \times 10^{-5}[/tex]

[tex]\to pKa = - \log \ Ka[/tex]

            [tex]= - \log \ 1.76 \times 10^{-5}\\\\ = 4.75[/tex]

[tex]pH = pKa + \log \frac{[sodium \ acetate]}{[acetic \ acid]}[/tex]

      [tex]= 4.75 + \log \frac{[0.123]}{[0.291]}\\\\= 4.75+ \lg(0.422680412)\\\\=4.75-0.373987878\\\\=4.37601212\\\\=4.37[/tex]

Answer:

NO + H₂O → HNO₂ + 1 e- + 1 H⁺

Step-by-step explanation:

NO ⇒ oxidation number of N = +2

HNO₂ ⇒ oxidation number of N= +3

Therefore, NO has to lose 1 electron to be oxidized to HNO₂. We write the half-reaction with 1 electron (1 e-) in the products side.

NO → HNO₂ + 1 e-

Now, we have 0 electrical charges in the reactants side, and a total of -1 electrical charge in the products side. As the reaction is in acidic aqueous solution, we have to add H⁺ ions to balance the charges. We perform the balance by adding 1 H⁺ (positive charge) to neutralize the negative charge in the side of the products:

NO → HNO₂ + 1 e- + 1 H⁺

Now, we perform the mass balance. We have:

N: 1 atom in both sides

O: 1 atom in reactants side and 2 atoms in products side

H: 0 atoms in reactants side, 2 atoms in products side.

Thus, we have to add 1 H₂O molecule to the reactants side to equal the masses:

NO + H₂O → HNO₂ + 1 e- + 1 H⁺

Finally, the oxidation half-reaction is:

NO + H₂O → HNO₂ + 1 e- + 1 H⁺

Answer:

O constant specific heat

Explanation:

Answer:

CaCO3 is the limiting reactant

55 g of CO2 is made

Explanation:

First we must put down the reaction equation;

CaCO3(s) + 2HCl(aq) ---------> CaCl2(s) + H2O(l) + CO2(g)

Number of mole of CaCO3 = 125g/100gmol-1 = 1.25 moles

From the reaction equation;

1 mole of CaCO3 yields 1 mole of CO2

Hence 1.25 moles of CaCO3 yields 1.25 moles of CO2

For HCl;

number of moles of HCl = 125g/36.5 g mol-1 = 3.42 moles

From the reaction equation;

2 moles of HCl yields 1 mole of CO2

3.42 moles of HCl yields 3.42 * 1/2 = 1.71 moles of CO2

Hence CaCO3 is the limiting reactant.

Mass of CO2 produced = 1.25g * 44 gmol-1 = 55 g of CO2

Answer:

47900 cm

General Formulas and Concepts:

Chemistry

Explanation:

Step 1: Define

0.479 km

Step 2: Identify Conversions

1 km = 1000 m

1 m = 100 cm

Step 3: Convert

[tex]0.479 \ km(\frac{1000 \ m}{1 \ km} )(\frac{100 \ cm}{1 \ m} )[/tex] = 47900. cm

Step 4: Check

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

47900. cm ≈ 47900 cm

Answer: it blue

Explanation:

Answer:

Positive

Explanation:

There are more protons than electrons making it positive

[tex]\bull\sf m=0.47kg[/tex]

[tex]\bull\sf \Delta T=T_f-T_i=48.4-30.5=17.9°C[/tex]

[tex]\bull\sf Q=1.65\times 10^4J[/tex]

We know according to thermodynamics

[tex]\\ \sf\longmapsto Q=mc\Delta T[/tex]

[tex]\\ \sf\longmapsto c=\dfrac{Q}{m\Delta T}[/tex]

[tex]\\ \sf\longmapsto c=\dfrac{1.65\times 10^4}{0.47\times 17.9}[/tex]

[tex]\\ \sf\longmapsto c=\dfrac{1.65\times 10^4}{8.413}[/tex]

[tex]\\ \sf\longmapsto c=0.1961\times 10^4J/kg°C[/tex]

[tex]\\ \sf\longmapsto c=1961J/kg°C[/tex]

Answer:

6.022×10²² molecules

Explanation:

Given data:

Volume of nitrogen = 224 L

Pressure = standard = 1 atm

Temperature = standard = 273 K

Number of molecules = ?

Solution:

PV = nRT

1 atm × 224 L = n × 0.0821 atm.L/mol.K × 273 K

224 atm.L = n ×22.41 atm.L/mol

n = 224 atm.L/22.41 atm.L/mol

n = 10 mol

1 mole contain 6.022×10²³ molecules

10 mol×6.022×10²³ molecules/ 1 mol

60.22×10²³ molecules

6.022×10²² molecules

Answer:

thank you! ladies... love the answer is A) 6.022 x 10 ^22

Explanation:

love this one!

have a good one everyone

Answer:

[tex]115.625^{\circ}\text{F}[/tex]

Explanation:

[tex]m_1[/tex] = First mass of water = 12 oz

[tex]m_2[/tex] = Second mass of water = 20 oz

[tex]\Delta T_1[/tex] = Temperature difference of the solution with respect to the first mass of water = [tex](T-75)^{\circ}\text{F}[/tex]

[tex]\Delta T_2[/tex] = Temperature difference of the solution with respect to the second mass of water = [tex](T-75)^{\circ}\text{F}[/tex]

c = Specific heat of water

As heat gain and loss in the system is equal we have

[tex]m_1c\Delta T_1=m_2c\Delta T_2\\\Rightarrow m_1\Delta T_1=m_2\Delta T_2\\\Rightarrow 12(T-75)=20(140-T)\\\Rightarrow 12T-900=2800-20T\\\Rightarrow 12T+20T=2800+900\\\Rightarrow 32T=3700\\\Rightarrow T=\dfrac{3700}{32}\\\Rightarrow T=115.625^{\circ}\text{F}[/tex]

The final temperature of the solution is [tex]115.625^{\circ}\text{F}[/tex].

Answer:

349 L (To 3 significant figures)

Explanation:

The reaction equation is;

C9H20(l) + 14O2(g) ------> 9CO2(g) + 10H2O(g)

number of moles of nonane in 0.210 Kg = mass/molar mass

molar mass of nonane = 9(12) + 20(1) = 128 gmol-1

Hence number of moles = 0.210 * 10^3g/128 gmol-1 = 1.64 moles

If 1 mole of nonane produced 9 moles of CO2 from the balanced reaction equation;

1.64 moles of nonane will produce 1.64 * 9/1 = 14.76 moles of CO2

Now from the ideal gas equation;

PV=nRT

P = 1 atm

V= the unknown

n= 14.76

R = 0.082 atmLmol-1K-1

T = 15 + 273 = 288 K

V= nRT/P

V = 14.76 * 0.082 * 288/1

V = 348.57 L

Answer:

The number of moles of formic acid needed is 4.5x10⁻³ moles.

Explanation:

We can find the moles of formic acid using the Henderson-Hasselbalch equation:

[tex] pH = pKa + log(\frac{[CHOO^{-}]}{[CHOOH]}) [/tex]

We know:

pH = 3.60

pKa = 3.75                    

By solving the above equation for [CHOO⁻]/[CHOOH] we have:

[tex] \frac{[CHOO^{-}]}{[CHOOH]} = 10^{(pH - pKa)} = 10^{(3.60 - 3.75)} = 0.71 [/tex]

[tex] [CHOO^{-}] = 0.71[CHOOH] [/tex]  (1)

Now, we have:

[tex] [CHOOH] + [CHOO^{-}] = 0.03 M [/tex]   (2)

By entering equation (1) into (2) we have:

[tex] [CHOOH] + 0.71[CHOOH] = 0.03 M [/tex]

[tex] [CHOOH] = 0.018 M [/tex]

Hence, the concentration of formate is:

[tex] [CHOO^{-}] = (0.03 - 0.018)M = 0.012 M [/tex]

Finally, the number of moles of formic acid is:

[tex] n_{CHOOH} = [CHOOH]*V = 0.018 \frac{mol}{L}*0.250 L = 4.5 \cdot 10^{-3} moles [/tex]

Therefore, 4.5x10⁻³ moles of formic acid are needed.

I hope it helps you!  

We have that for the Question "How many moles of formic acid will you need?"

It can be said that

From the question we are told

to prepare 250.0 mL of a pH=3.60, total buffer concentration of formic acid + formate of 0.030 M, The pKa of formic acid is 3.75.

Let [tex]1+COO4 = X, 1+COON = (0.03-X)[/tex]

[tex]pH = pKa + log\frac{1+COON}{1+COO4}\\\\3.6 = 3.75 +log\frac{0.03-X}{X}\\\\log\frac{0.03-X}{X} = 3.6 - 3.75\\\\\frac{0.03-X}{X} = 0.708\\\\X = 0.0175M[/tex]

Therefore,

[tex]moles of formic acid = 0.0175*0.25mole\\\\= 4.39*10^{-3}mole[/tex]

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Answer:

The original concentration of the HCl is: 0.01925 M

Explanation:

Equation:

HCl+NaOH-------> NaCl+H₂O

Volume of NaOH added = 0.05 M

No of moles of NaOH = 15.4 mL [tex]x\frac{1 L}{1000 mL} x\frac{0.05 mol NaOH}{L}[/tex]

= 0.00077 mol NaOH

Then,

Volume of HCl solution = 40 mL x 1/1000 mL

= 0.0400 L

Therefore,

Concentration of HCl = 0.00077 mol/0.0400 L

= 0.01925 M

Now, to find the pH:

pH = -log₁₀[H⁺]

     = -log₁₀(2x10⁻⁶)

     = 5.7

Answer:

the water has been poulutid due to all of the construction and debris that might have flown into the water.

Explanation:

Answer:

–156 °C

Explanation:

The following data were obtained from the question:

Initial temperature (T1) = –20 °C

Initial volume (V1) = 140 mL

Final volume (V2) = 65 mL

Final temperature (T2) =?

Pressure = constant.

Next, we shall convert –20 °C to Kelvin temperature. This can be obtained as follow:

T(K) = T(°C) + 273

Initial temperature (T1) = –20 °C

Initial temperature (T1) = –20 °C + 273 = 253 K.

Next, we shall determine the new temperature of the gas as follow:

Initial temperature (T1) = 253 K

Initial volume (V1) = 140 mL

Final volume (V2) = 65 mL

Final temperature (T2) =?

V1/T1 = V2/T2

140/253 = 65/T2

Cross multiply

140 × T2 = 253 × 65

140 × T2 = 16445

Divide both side by 140

T2 = 16445 /140

T2 = 117 K

Finally, we shall convert 117 K to celcius temperature. This can be obtained as follow:

T(°C) = T(K) – 273

T2 = 117 K

T2 = 117 K – 273

T2 = –156 °C

Thus, the new temperature of the gas is –156 °C

Answer:

That's not possible. When a limiting reactant is called out in a stoichiometry problem, what that means is there's enough of all the other reactants for the limiting one to be completely consumed in the formation of product/products

Answer:

Such a relationship between atomic number and atomic radius is a direct correlation. an inverse correlation. According to Coulomb's Law, as the atomic number increases within a series of atoms, the nuclear attraction for electrons will also increase, thus pulling the electron(s) closer to the nucleus.

Explanation:

Answer:

oxygen, silicon, iron, calcium, sodium

Explanation:

these are all found in space rocks known as meteorites. hope this helps :)

Answer:

a. 122.6 mL / pH = 4.03

b. 193.6 mL / pH = 5.73

Explanation:

In the equivalence point we know: mmoles acid = mmoles base- And the pH in a titration between a weak base and a strong base, is acid, at the equivalence point. For the volume, we can replace the equation with the data given.

a. 0.125M . volume of acid = 65.5 mL . 0.234M

Volume of acid = (65.5 . 0.234) / 0.125 = 122.6 mL

Total volume at the equivalence point = 188.1 mL

b. 0.125M . volume of acid = 21.8 mL . 1.11 M

Volume of acid = (21.8 .  1.11) / 0.125 = 193.6 mL

Let's calculate the pH. In the equilavence point we have a neutralization reaction.

a. NH₃ + HCl → NH₄Cl

All the mmoles of protons (65.5 mL . 0.234M) react to ammonia, to obtain ammonium.

New concentration is: 15.32 mmoles / 188.1 mL = 0.0814 M

This is the [NH₄⁺] to determine the pH in the acid base equilibrium.

NH₄⁺  +  H₂O  ⇄  NH₃  +  H₃O⁺      Ka

Expression for Ka = [NH₃]  . [H₃O⁺] / [NH₄⁺]

5.6×10⁻¹⁰ = x² / (15.32 - x)

(We can avoid the quadratic equation 'cause Ka is so small)

√(5.6×10⁻¹⁰ . 15.32) = x → [H₃O⁺] = 9.26×10⁻⁵

pH = - log [H₃O⁺] → 4.03

b. CH₃NH₂ + HCl → CH₃NH₃Cl

All the mmoles of protons (21.8 mL . 1.11M) react to methylamine, to obtain methylammonium.

New concentration is: 24.2 mmoles / 193.6 mL = 0.125 M

This is the [CH₃NH₃⁺] to determine the pH in the acid base equilibrium.

CH₃NH₃⁺  +  H₂O  ⇄  CH₃NH₂  +  H₃O⁺      Ka

Expression for Ka = [CH₃NH₂]  . [H₃O⁺] / [CH₃NH₃⁺]

2.7×10⁻¹¹ = x² / (0.125 - x)

(We can avoid the quadratic equation 'cause Ka is so small)

√(2.7×10⁻¹¹ . 0.125) = x → [H₃O⁺] = 1.84×10⁻⁶

pH = - log [H₃O⁺] → 5.73

The pH of the equivalence point of 0.125M HCl with NH₃ is 4.03 and with CH₃NH₂ is 5.73.

In the acid - base titration, at the equivalence point equal moles of acid as well as of base are present.

First we calculate the volume of HCl by using the below equation as:

M₁ = molarity of NH₃ = 0.234 M

V₁ = volume of NH₃ = 65.5 mL

M₂ = molarity of HCl = 0.125 M

V₂ = volume of HCl = ?

V₂ =  (65.5 . 0.234) / 0.125 = 122.6 mL

Total volume at the equivalence point = 188.1 mL

Chemical reacion will be written as:

NH₃ + HCl → NH₄Cl

All moles of protons react with moles of ammonia, so new moles (n) will be calculated as:

n = molarity × volume

n = 65.5 mL × 0.234M = 15.32 moles

Now, concentration in terms of molarity will be 15.32 mmoles / 188.1 mL = 0.0814 M

pH in the acid-base reaction due to [NH₄⁺], as:

NH₄⁺  +  H₂O  ⇄  NH₃  +  H₃O⁺

Value of Ka for this reaction is = 5.6×10⁻¹⁰

According to the ICE table, Ka equation will be written as-

5.6×10⁻¹⁰ = x² / (15.32 - x)

x = [H₃O⁺] = 9.26 × 10⁻⁵

pH = - log [H₃O⁺] = 4.03

0.125M . volume of acid = 21.8 mL . 1.11 M

Volume of acid = (21.8 .  1.11) / 0.125 = 193.6 mL

Total volume at the equivalence point = 215.4 mL

Chemical reacion will be written as:

CH₃NH₂ + HCl → CH₃NH₃Cl

All moles of protons react with moles of ammonia, so new moles (n) will be calculated as:

n = 21.8 mL . 1.11M = 24.2 moles

Now, concentration in terms of molarity will be 24.2 moles / 215.4 mL = 0.11M

pH in the acid-base reaction due to [CH₃NH₃⁺], as:

CH₃NH₃⁺  +  H₂O  ⇄  CH₃NH₂  +  H₃O⁺

Value of Ka = 2.7×10⁻¹¹

According to the ICE table, Ka equation will be written as-

2.7×10⁻¹¹ = x² / (0.11 - x)

x = [H₃O⁺] = 5.4×10⁻⁶

pH = - log [H₃O⁺] = 5.73

Hence the value of pH will be 4.03 and 5.73 respectively.

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There is a golden role of solubility, polar solute dissolve in polar solvent and non polar solute dissolve in non polar solvent. Therefore, the correct option is option B that is Salt and water.

Solutions are a homogeneous mixture of two or more substances. A solution is a homogeneous mixture of solvent and solute molecules. Solvent is a substance that is in large amount in solution. solute is the substance which is in small amount in a solution. There are two types of mixture that is homogeneous and heterogeneous. Solution is a homogeneous solution.

Salt and water because salt is transparent and will dissolve into the water among given solute, salt NaCl is a polar solute which will dissolve in polar solvent that is water.

Therefore, the correct option is option B that is Salt and water.

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Answer:

someone is in my mind and it is telling me 5.55m

Explanation:

Answer:

4 mL

Explanation:

4mL is 5% of 80mL. Therefore my answer is right.

The atomic radius trend on the Periodic Table is as follows:

- Atomic radius increases down a column (or group)

- Atomic radius decreases across rows (or periods) from left to right

Looking at my Periodic Table, calcium, chromium, cobalt and copper are in that order from left to right in the same period, which simplifies things significantly.

Since these elements are in the same period, and given that we know atomic radius decreases across periods from left to right, we can see that calcium has the largest atomic radius.

Answer:

See explanation and image attached

Explanation:

The addition of hypohalous acids to alkenes follows the Markovnikov rule. This rule states that the negative part of the addendum is joined to the carbon atom with the least number of hydrogen atoms (more substituted carbon atom).

In the addition of hypohalous acids, the halogen is the positive end of the addendum and the OH^- is the negative end of the addendum. This explains the product shown in the image attached.

Answer:

16mL.

Explanation:

From the Question above we have the following parameters/information which is going to help in solving this particular Question;

=> The mass methyl acetate that the student needed is = 15.0g.

=> The density of methyl acetate given is = 0.934 g/mL. (Kindly remember that formula for Determining density of a particular substance = density = mass/volume.

Hence, the volume of methyl acetate needed to be poured away can be calculated from the formula for calculating density.

Density = mass/ volume.

Density = 0.934 g/mL., and mass = 15.0g. Therefore, the volume = mass/density.

Volume = 15.0g/ 0.934 g/mL = 16 mL.

Answer:

The average atomic mass is closer to Si- 28 because this isotope is present in more percentage in the sample.

Explanation:

Given data:

Atomic mass of silicon= ?

Percent abundance of Si-28 = 92.21%

Atomic mass of Si-28 = 27.98 amu

Percent abundance of Si-29 = 4.70%

Atomic mass of  Si-29 = 28.98 amu

Percent abundance of Si-30 = 3.09%

Atomic mass of  Si-30 = 29.97 amu

Solution:

Average atomic mass = (abundance of 1st isotope × its atomic mass) +(abundance of 2nd isotope × its atomic mass)+(abundance of 2nd isotope × its atomic mass)  / 100

Average atomic mass = (92.21×27.98)+(4.70×28.98)+(3.09×29.97) /100

Average atomic mass =  2580.04 +136.21+92.61 / 100

Average atomic mass = 2808.86 / 100

Average atomic mass  = 28.08amu.

The average atomic mass is closer to Si- 28 because this isotope is present in more percentage in the sample.

Answer:

The average atomic mass of silicon would be closer to Si-28 as it is the most abundant isotope.

Explanation:

From PLATO

Answer:

See explanation

Explanation:

Substances are composed of bands. A band is a group of molecular orbitals, the energy differences between them are so small that the system behaves as if a continuous, non-quantization of energy within the barrier is possible.

Materials consists of a valence band and a conduction band separated by a band gap. A band gap occurs when the energy difference between two bands is significant.

The magnitude of band gap determines whether a material will be a metal, nonmetal or metalloid.

Metals have a very little band gap hence they are able to conduct electricity more effectively than other materials, such as ionic and covalent substances.