19. A beam of light can be seen as it passes through a(n).
a. Element
I
b. Compound
C. Solution
d. Heterogeneous Mixture
A beam of light can be seen as it passes through a

Answer:

Explanation:

Caffeine is a weak base with pKb = 10.4

Kb = 10⁻¹⁰°⁴ = 3.98 x 10⁻¹¹

molecular weight of caffeine = 194.2

455 x 10⁻³ g / L = 455 x 10⁻³ / 194.2 moles / L

concentration of given solution a = 2.343 x 10⁻³ M

Let the caffeine be represented by B .

B    +   H₂O =  BH + OH⁻

a - x                   x        x  

x² / ( a - x ) = Kb

x² / ( a - x ) = 3.98 x 10⁻¹¹

x is far less than a so a -x is almost equal to a

x² = 3.98 x 10⁻¹¹ x 2.343 x 10⁻³ = 9.32  x 10⁻¹⁴

x = 3.05 x 10⁻⁷

[ OH⁻ ] = 3.05 x 10⁻⁷

pOH = - log ( 3.05 x 10⁻⁷ )

= 7 - log 3.05

= 7 - 0.484 = 6.5

pH = 14 - 6.5 = 7.5  

The pH of 455 mg/L of caffeine is 7.5

Using the formula;

Mass concentration = molar concentration × molar mass

Molar mass of caffeine = 194 g/mol

Mass concentration of caffeine = 455 mg/L

Molar concentration = Mass concentration/molar mass

Molar concentration = 455 × 10^-3g/L/194 g/mol

= 0.00235 M

Let Caffeine by depicted by the general formula BH

We can now set up the ICE table as follows;

           :B + H2O   ⇄ BH       +       OH^-

I      0.00235              0                      0

C           - x                  +x                    +x

E    0.00235  - x           x                      x

Note that water is present in large excess

Again; pKb of caffeine =10.4

Kb = Antilog[-pKb]

Kb = Antilog [-10.4]

Kb = 3.98 × 10^-11

Kb = [BH] [OH^-]/[:B]

3.98 × 10^-11 = [x] [x]/[ 0.00235  - x  ]

3.98 × 10^-11 [ 0.00235  - x  ] = [x] [x]

9.4 × 10^-14 - 3.98 × 10^-11x = x^2

x^2 + 3.98 × 10^-11x  - 9.4 × 10^-14 = 0

x = 3.1 × 10^-7 M

Recall  [BH] = [OH^-] = 3.1 × 10^-7 M

Now;

pOH = - log [OH^-]

pOH = log [3.1 × 10^-7 M]

pOH = 6.5

But;

pH + pOH = 14

pH = 14 - pOH

pH = 14 - 6.5

pH = 7.5

The pH of 455 mg/L of caffeine is 7.5

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Missing parts

Caffeine (C8H10N4O2) is a weak base with a pKb of 10.4.  Calculate the pH of a solution containing a caffeine concentration  of 455 mg/L.

Answer:

= .7567105263

Explanation:

1 atm = 760 mmHg

575.1 mmHg (1 atm/760mmHg) = .7567105263 atm

Answer:

F - O - S - Mg - Ba

Explanation:

as you move left to right on the periodic table the number of electrons increase.

The correct lists of the five atoms in order of increasing size smallest to

largest is :

D) F - O - S - Mg - Ba

The correct lists of the five atoms in order of increasing size smallest to

largest is F - O - S - Mg - Ba.

The atomic radius of a chemical element may be a degree of the measure of its molecule, as a rule the mean or commonplace remove from the center of the core to the furthest isolated electron.

The arrange will be:

As you move cleared out to right on the periodic table the number of electrons increment.

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Answer:

Explanation:

Here you go!! Hope this helps.

Answer:

A. the wave is a mechanical wave

C. the wave moves energy through matter

F: the wave transfers energy perpendicular to the motion of the wave.

Answer:

[tex]\%sand=25\%[/tex]

Explanation:

Hello.

In this case, given the mass of the mixture, we can define it in terms of the mass of sand and table salt as shown below:

[tex]m_{sand}+m_{salt}=20.00g[/tex]

Moreover, as after filtering, the mass of dry sand turns out 5.00 g, we can compute the % sand in the original mixture by dividing this value over the mass of the mixture as shown below:

[tex]\%sand=\frac{m_{sand}}{m_{mixture}}*100\%\\ \\\%sand=\frac{5.00g}{20.00g}* 100\%\\\\\%sand=25\%[/tex]

Best regards!

Answer:

10 moles of water are produced,

Explanation:

Given data:

Moles of H = 10 mol

Moles of O = 6 mol

Water obtained = ?

Solution:

Balance chemical equation:

2H₂ + O₂    →    2H₂O

Now we will compare the moles of H₂ and O₂ with water from balance chemical equation.

                            H₂             :          H₂O

                             2              :            2

                             10             :           10

                            O₂             :          H₂O

                             1              :            2

                             6             :           2×6 = 12

Number of moles of water produced by hydrogen are less so hydrogen will be limiting reactant and it will limit the yield of water thus, 10 moles of water are produced.

Answer:

Waves is the disturbance or variation that transfer energy from one location to other

Answer:

this is not in my words but i think this will help

(put some of the words you would use in this)

Explanation:

Transverse waves are always characterized by particle motion being perpendicular to wave motion. A longitudinal wave is a wave in which particles of the medium move in a direction parallel to the direction that the wave moves. ... Longitudinal waves are always characterized by particle motion being parallel to wave motion.

hope i helped

Answer:

What Is The Molecular Shape Of A Silicon Disulfide Molecule, SiS2 Trigonal Planar None Of Above Tetrahedral Linear Bent Trigonal Pyramidal 13.

Explanation:

The Lewis structure of SiS₂ shows the 4 valence electrons of Si, which are shared with each sulphur atoms and sulphur in turn shares two valence electrons with Si atom.

The Lewis dot structure of a compound shows all the valence electrons as dots around its atom. From the dot structure  we can identify, which electron pairs are bonded , which are non-bonded and which are unpaired electrons.

SiS₂ is a covalent compound formed through the electrons sharing between two  sulphur and one silicon atoms. The silicon atom contains 4 valence electrons and one sulphur atom contains 6 valence electrons.

Si needs to gain 4 electrons and one S atom needs to gain 2 more electrons into their valence shell to achieve octet. Hence, One Si shares two electron to each S and S in turn shares its two electron with Si as shown in the image below.

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Answer:

Insoluble benzoic acid is formed

Explanation:

When benzoic acid is dissolved in sodium hydroxide solution, sodium benzoate is formed. This compound is highly soluble in the aqueous layer.

If this solution is now acidified, the equilibrum position shifts towards the undissociated benzoic acid and a precipitate appears.

An insoluble substance formed during crystallization or precipitation is called a precipitate. The precipitate of the reaction formed is of benzoic acid.

A precipitation reaction is a type of reaction in which an insoluble salt or substance is formed as the result of the reaction between the soluble salt solutions.

The substance or the salt produced that does not get dissolved in the solution is called a precipitate.

In the reaction, benzoic acid reacts with the sodium hydroxide salt and forms sodium benzoate salt as shown,

[tex]\rm C_{6}H_{5}COOH(s) + NaOH(aq) \rightarrow C_{6}H_{5}COO^{-}Na^{+}(aq) + H_{2}O(l)[/tex]

When the salt of sodium benzoate is acidified then the precipitation of benzoic acid is formed. The precipitate occurs because the equilibrium shifts towards the undissociated benzoic acid.

Therefore, a precipitate of benzoic acid is formed.

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Answer:

∠

O

−

C

−

C

l

≅

120

∘

The central carbon is  

s

p

2

−

hybridized........

Explanation:

And thus  

∠

C

l

−

C

−

C

l

and  

∠

O

−

C

−

C

l

≅

are  

120

∘

to a first approximation.

Why this value? We look to  

VSEPR theory

. There are 3 regions of electron density around the central carbon, and the most stable geometry is a trigonal plane. While there is a  

carbonyl

group, i.e. a  

C

=

O

bond, the  

π

bond is conceived to lie above and below this trigonal plane.

The  

carbonyl oxygen

is likewise conceived to be  

s

p

2

-hybridized

, however, here, there are 2 lone pairs on the oxygen centre.

The approximate chlorine-carbon-chlorine bond angle in C2Cl4 is 120°.

The bond angle is defined as the angle between ant two bonds emanating from a common atom.

The compound C2Cl4 is tetrachloroethene. The carbon atoms are sp2 hybridized in this molecule.

Recall that the bond angle of an sp2 hybridized carbon atom is 120°. Therefore the chlorine-carbon-chlorine bond angle in C2Cl4 is 120°.

From the perspective of the VSEPR theory, the geometry of each carbon atom in C2Cl4 is trigonal planar which implies a bond angle of 120°.

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Answer:

The equilibrium concentration of NO is 0.02124 M.

Explanation:

Given that,

Initial concentration of NOBr = 0.878 M

[tex]k_{c}=3.07\times10^{-4}[/tex]

Temperature = 24°C

We know that,

The balance equation is

[tex]2NOBr\Rightarrow 2NO+Br_{2}[/tex]

Initial concentration is,

[tex]0.878\Rightarrow 0+0[/tex]

Concentration is,

[tex]-2x\Rightarrow 2x+x[/tex]

Equilibrium concentration

[tex]0.878-2x\Rightarrow 2x+x[/tex]

We need to calculate the value of x

Using formula of concentration

[tex]k_{c}=\dfrac{[NO][Br_{2}]}{[NOBr]^2}[/tex]

Put the value into the formula

[tex]3.07\times10^{-4}=\dfrac{[2x][x]}{[0.878-2x]^2}[/tex]

[tex]2x^2=3.07\times10^{-4}\times(0.878)^2+3.07\times10^{-4}\times4x^2-2\times2x\times0.878\times3\times10^{-4}[/tex]

[tex]2x^2=0.0002367+0.001228x^2-0.0010536x[/tex]

[tex]2x^2-0.001228x^2+0.0010536x-0.0002367=0[/tex]

[tex]1.998772x^2+0.0010536x-0.0002367=0[/tex]

[tex]x=0, 0.01062[/tex]

We need to calculate the equilibrium concentration of NO

Using formula of concentration of NO

[tex]concentration\ of\ NO=2x[/tex]

Put the value of x

[tex]concentration\ of\ NO=2\times0.01062[/tex]

[tex]concentration\ of\ NO=0.02124[/tex]

Hence, The equilibrium concentration of NO is 0.02124 M.

Answer:

the ball will move towards the big bully

Explanation:

heat

the presence of hot, plastic like material

Answer:

What are we talking about here?

Explanation:

Answer:

valence electrons

Explanation:

other guy was close enough

Atoms of elements in the same group have the equal number of valence electrons. That is why they have similar chemical properties.

The chemical properties of elements depend on the number of valence electrons in their outermost shell. Those elements which are placed in the same group in the periodic table have the same number of valence electrons.

Therefore, elements present in the same group of the modern periodic table have similar chemical behavior.

The elements having a similar valence shell electronic configuration in their atoms are arranged in the same group of the periodic table. These valence electrons decide the chemical properties and reactivities of the chemical elements.

For example, all the elements in group 1 of the periodic table have one electron in their valence shell and all the elements present in group 17 have seven electrons in their valence shell.

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Answer:

Nucleus

Explanation:

The nucleus because it is basically the control system for the cell.

Answer:

Explanation:

Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA).

https://medlineplus.gov/genetics/understanding/basics/dna/

Answer:

Amount of salt dissolved in each liter of seawater = 40 g

Explanation:

According to Archimedes principle, a body will float in a fluid if the upthrust experienced by a body is equal to the to the weight of the body.

Also, the volume of seawater displaced equals the volume of freshwater in the cup.

From the above principle, since the freshwater and cup floats in the seawater, their combined weight equals the upthrust.

Therefore, mass of equal volume of displaced seawater = mass of freshwater + mass of cup

Mass of freshwater = density of freshwater * volume

density of freshwater = 1 g/mL; volume = 375 mL

mass of freshwater = 375 mL * 1 g/mL = 375 g

mass of seawater = 375 + 15 = 390 g

mass of salt in 375 mL seawater = mass of seawater - mass of freshwater

mass of salt = (390 - 375) g = 15 g

Since 15 g of salt are dissolved in 375 mL seawater, mass of salt in 1 L of seawater =(1000 mL/ 375) * 15g = 40 g

Therefore, amount of salt dissolved in each liter of seawater = 40 g

Answer:

35.1% is percent yield

Explanation:

Full question: Assume no volume change.  If you formed 0.0910 atm of gas, what is the percent yield?

The reaction that is occurring is:

Ni + 3HBr → NiBr₃ + 3/2H₂(g)

First, we will determine moles of Ni and HBr to determine limiting reactant and theoretical yield

Using ideal gas law, we can determine the moles of hydrogen formed. Thus, we can find percent yield:

Moles Ni (Molar mass: 58.69g/mol):

1.02g * (1mol / 58.69g) = 0.01738moles Ni

Moles HBr:

0.750L * (0.112mol/L) = 0.084 moles of HBr.

For a complete reaction of the 0.084 moles of HBr you need:

0.084mol HBr * (1 mole Ni / 3 moles HBr) = 0.028 moles of Ni.

As there are just 0.01738 moles of Ni, the Ni is limiting reactant. Assuming a theoretical yield, moles of H₂ produced are:

0.01738moles Ni * (3/2 H₂ / 1 mol Ni) = 0.02607 moles H₂

Now, moles of H₂ produced are:

PV = nRT

PV/RT = n

Where P is pressure (0.0910atm)

V is volume (2.50L)

R is gas constant (0.082atmL/molK)

T is absolute temperature in Kelvin (30°C + 273.15 = 303.15K)

And n are moles

PV/RT = n

0.0910atm*2.50L/0.082atmL/molK*303.15K = n

0.00915 moles = n

And percent yield (Produced moles / Theoretical moles * 100) is:

0.00915 moles / 0.02607moles =

Answer:

C

Explanation:

matter is anything that has mass and volume...it has three state thus solid, liquid and gas.. It possess chemical and physical changes.

Answer:

Titanium [Ar] 3d2 4s2

Explanation:

Answer:

Radioactive decay

Explanation:

Answer:

D. Radioactive decay

Explanation: