Ask question

Ask question

All categories

Artyom0805 [142]

2 years ago

8

The model of the atom where the central core contains protons and neutrons surrounded by a cloud of electrons is best described

as A) The Bohr model of the atom. B) The modern model of the atom. C) The plum pudding model of the atom. D) The solar system model of the atom.

2 answers:

noname [10]2 years ago

6 0

The modern model of the atom B)

WITCHER [35]2 years ago

4 0

I am thinking the answer is B. I think this because Bohr had a model similar, but his was lacking the cloud of electrons. His just had electrons orbiting the nucleus.
I hope this is right!<span />

You might be interested in

On a summer day, you take a road trip through Death Valley, California, in an antique car. You start out at a temperature of 21°

MrRissso [65]

<span>There is only one formula to use and we should assume ideal gas. This equation is: PV=nRT. For the following questions manipulate this equation to get the answer.
1. n = PV/RT = (249*1000 Pa)(15.6 L)(1 m^3/1000 L)/(8.314 Pa-m^3/mol-K))(21+273) = 1.59 mol
2. P = nRT/V = (1.59)(8.314)(51+273)/(15.6/1000)(1000) = 274.55 kPa
3. Since the answer in #2 is more than 269 kPa, then the tires will likely burst. 4. Reduce pressure way below the limit 269 kPa.</span>

4 0

2 years ago

What is the pH of a solution prepared by mixing 50.00 mL of 0.10 M methylamine, CH3NH2, with 20.00 mL of 0.10 M methylammonium c

olya-2409 [2.1K]

Answer:

pH=10.97

Explanation:

the solution of methyl amine with methylammonium chloride will make a buffer solution.

The pH of buffer solution can be obtained using Henderson Hassalbalch's equation, which is:

$pOH=pKb+log\frac{[salt]}{[base]}$

pH = 14- pOH

Let us calculate pOH $pOH=3.43+ (-0.397)=3.03$

$pH=14-pOH=14-3.03=10.97$

[Salt] = [methylammonium chloride] = 0.10 M (initial)

After adding base

$[salt] = \frac{molarityXvolume}{finalvolume}=\frac{0.1X20}{(20+50)}= 0.0286M$

[base] = [Methylamine]=0.10

After mixing with salt

$[base]= \frac{molarityXvolume}{finalvolume}=\frac{0.1X50}{(20+50)}= 0.0714M$

pKb= -log[Kb]= 3.43

Putting values

pOH = $3.43+log(\frac{[0.0286]}{0.0714}$

4 0

2 years ago

10 points) Given the following two half-reactions, write the overall reaction in the direction in which it is product-favored, a

IceJOKER [234]

Answer:

The over all reaction :

$2Fe^{3+}(aq)+Pb(s)\rightarrow 2Fe^{2+}(s)+Pb^{2+}(aq)$

The standard cell potential of the reaction is 0,.897 Volts.

Explanation:

Reduction at cathode :

$Fe^{3+}(aq)+e^-\rightarrow Fe^{2+}(s)$ ..[1]

$E^o_{Fe^{3+}/Fe^{2+}}=0.771 V$

Reduction potential of $Fe^{3+}$ to $Fe^{2+}=0.771 V$

Oxidation at anode:

$Pb(s)\rightarrow Pb^{2+}(aq)+2e^-$ .[2]

$E^o_{Pb^{2+}/Pb}=-0.126 V$

Reduction potential of $Pb^{3+}$ to $Pb=-0.126 V$

To calculate the $E^o_{cell}$ of the reaction, we use the equation:

$E^o_{cell}=E^o_{red,cathode}-E^o_{red,anode}$

Putting values in above equation, we get:

$E^o_{cell}=E^o_{Fe^{3+}/Fe^{2+}}-E^o_{Pb^{2+}/Pb}$

$=0.771 V-(-0.126 )=0.897 V$

The over all reaction : 2 × [1] + [2]

$2Fe^{3+}(aq)+Pb(s)\rightarrow 2Fe^{2+}(s)+Pb^{2+}(aq)$

The standard cell potential of the reaction is 0,.897 Volts.

7 0

2 years ago

Zinc is to be electroplated onto both sides of an iron sheet that is 20 cm2 as a galvanized sacrificial anode. It is desired to

Alexandra [31]

Answer:

The time required for the coating is 105 s

Explanation:

Zinc undergoes reduction reaction and absorbs two (2) electron ions.

The expression for the mass change at electrode $(m_{ch})$ is given as :

$\frac{m_{ch}}{M} ZF = It$

where;

M = molar mass

Z = ions charge at electrodes

F = Faraday's constant

I = current

A = area

t = time

also; $(m_{ch})$ = $(Ad) \rho$ ; replacing that into above equation; we have:

$\frac{(Ad) \rho}{M} ZF = It$ ---- equation (1)

where;

A = area

d = thickness

$\rho$ = density

From the above equation (1); The time required for coating can be calculated as;

$[ \frac{20 cm^2 *0.0025 cm*7.13g/cm^3}{65.38g/mol}*2 \frac{moles\ of \ electrons}{mole \ of \ Zn} * 9.65*10^4 \frac{C}{mole \ of \ electrons } ] = (20 A) t$

$t = \frac{2100}{20}$

= 105 s

8 0

2 years ago

Many free radicals combine to form molecules that do not contain any unpaired electrons. The driving force for the radical–radic

Alexxandr [17]

Answer:

In the attached image the Lewis equation is shown where it is shown how two oxygens react with two hydrogens to meet the octet of the electrons.

Explanation:

Hydrogen peroxide is one of the most named chemicals since it is not only sold as "hydrogen peroxide" in pharmacies but it is also one of the great weapons of immune defense cells to defend ourselves against anaerobic bacteria.

The disadvantage of this compound is that when dividing it forms free oxygen radicals that are considered toxic or aging for our body.

4 0

2 years ago