What is the density of a rectangle solid with dimensions

U-238 has _____ protons and 146 neutrons

qaws [65]

U-238
The number besides the U means its total molar mass. The molar mass of this element is 238
Molar mass= protons + neutrons
This means that 238= 146 + protons
Do 238 - 146
Answer is 92

6 0

3 years ago

Which of the following statements regarding alpha particles are true? Check all that apply.a. Alpha particles have a mass number

egoroff_w [7]

Answer:

The only true statement is:

a. Alpha particles have a mass number of 4

Explanation:

Alpha particles are radiactive particles equivalent to a helium nucleus, so they have two protons and two neutrons.

Hence, alpha particles, α, are represented as:

⁴₂He

The superscript 4 to the left of the chemical symbol is the mass number: 2 protons + 2 neutrons = 4

The subscript 2 to the left of the chemical symbol is the atomic number: 2 protons = 2.

Hence, the statement "a. Alpha particles have a mass number of 4" is true.

As for the other statements, you have:

b. Alpha particles have a nulear charge of +1: false

Since, these particles are the nucleous of the helium atom, the nuclear charge equals the number of protons of this atom: +2. Hence, the statement is false.

c. Alpha particle formation is accompanied by the conversion of a proton into a neutron and d. Alpha particle formation is accompanied by the conversion of a neutron into a proton. (both false)

The conversion of a protons into a neutrons and the conversion of a neutron into a proton are product of other kind of radiactive desintegrations.

The conversion of a proton into a neutron involves the emission of a positron ( particle with same mass as the electron but positive charge) from the nucleus, which is represented as ⁰₊₁β.

The conversion of a neutron into a proton involves the emssion of an electron from the nucleus, which is the emission of a beta particle represented as ⁰₋₁β.

Therefore, these last two statements are also false.

4 0

3 years ago

You have a solution of 600 mg of caffeine dissolved in 100 mL of water. The partition coefficient for aqueous caffeine extracted

klio [65]

Answer:

159 mg caffeine is being extracted in 60 mL dichloromethane

Explanation:

Given that:

mass of caffeine in 100 mL of water = 600 mg

Volume of the water = 100 mL

Partition co-efficient (K) = 4.6

mass of caffeine extracted = ??? (unknown)

The portion of the DCM = 60 mL

Partial co-efficient (K) = $\frac{C_1}{C_2}$

where; $C_1=$ solubility of compound in the organic solvent and $C_2$ = solubility in aqueous water.

So; we can represent our data as:

$K=(\frac{A_{(g)}}{60mL} )$ ÷ $(\frac{B_{(mg)}}{100mL} )$

Since one part of the portion is A and the other part is B

A+B = 60 mL

A+B = 0.60

A= 0.60 - B

4.6= $(\frac{0.6-B(mg)}{60mL} )$ ÷ $(\frac{B_{(mg)}}{100mL})$

4.6 = $\frac{(\frac{0.6-B(mg)}{60mL} )}{(\frac{B_{(mg)}}{100mL})}$

4.6 × $(\frac{B_{(mg)}}{100mL})$ = $(\frac{0.6-B(mg)}{60mL} )$

4.6 B $*\frac{60}{100}$ = 0.6 - B

2.76 B = 0.6 - B

2.76 + B = 0.6

3.76 B = 0.6

B = $\frac{0.6}{3.76}$

B = 0.159 g

B = 159 mg

∴ 159 mg caffeine is being extracted from the 100 mL of water containing 600 mg of caffeine with one portion of in 60 mL dichloromethane.

4 0

3 years ago

Read 2 more answers

Could volume by displacement be used to determine the volume of a lump of rock salt? Explain would be nice

Readme [11.4K]

Yes it could, but you'd have to set up the process very carefully.
I see two major challenges right away:

1). Displacement of water would not be a wise method, since rock salt
is soluble (dissolves) in water. So as soon as you start lowering it into
your graduated cylinder full of water, its volume would immediately start
to decrease. If you lowered it slowly enough, you might even measure
a volume close to zero, and when you pulled the string back out of the
water, there might be nothing left on the end of it.

So you would have to choose some other fluid besides water ... one in
which rock salt doesn't dissolve. I don't know right now what that could
be. You'd have to shop around and find one.

2). Whatever fluid you did choose, it would also have to be less dense
than rock salt. If it's more dense, then the rock salt just floats in it, and
never goes all the way under. If that happens, then you have a tough
time measuring the total volume of the lump.

So the displacement method could perhaps be used, in principle, but
it would not be easy.

5 0

3 years ago

Solid state transformation?

Drupady [299]

A solid-state phase transformation occurs when the interface between two grains that are chemically or structurally different moves.

3 0

3 years ago

Read 2 more answers