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Natasha_Volkova [10]

3 years ago

11

Jolene wants to experiment with sugar cubes. Which of the following causes a sugar cube to only change physically, not chemicall

y

1 answer:

Ugo [173]3 years ago

5 0

If you cut the cube and keep all the pieces you are causing only physical change

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The initial activity of 37Ar is 8540 disintegrations per minute. After 10.0 days, the activity is 6990 disintegrations per minut

mylen [45]

Answer:

Approximately 3318 disintegrations per minute.

Explanation:

The activity $A$ of a radioactive decay at time $t$ can be found with the following equation:

$\displaystyle A(t) = A_0 \cdot \mathrm{e}^{-\lambda\cdot t}$ .

In this equation,

$\mathrm{e}$ is the natural base. $\mathrm{e}\approx 2.71828$ .
$A_0$ is the initial activity of the decay. For this question, $A_0 = \rm 8540\; min^{-1}$ .
The decay constant $\lambda$ of this sample needs to be found.

The decay constant here can be found using the activity after 10 days. As long as both times are in the same unit (days in this case,) conversion will not be necessary.

$A(10) = A_0\cdot \mathrm{e}^{\rm -\lambda \times 10\;day}= (\mathrm{8540\; min^{-1}})\cdot \mathrm{e}^{\rm -\lambda \times 10\;day}$ .

$A(10) = \rm 6690\; min^{-1}$ .

$\displaystyle \frac{\rm 6690\; min^{-1}}{\mathrm{8540\; min^{-1}}} = \mathrm{e}^{\rm -\lambda \times 10\;day}$

Apply the natural logarithm to both sides of this equation.

$\displaystyle \ln{\left(\frac{\rm 6690\; min^{-1}}{\mathrm{8540\; min^{-1}}}\right)} = \ln{\left(\mathrm{e}^{\rm -\lambda \times 10\;day}\right)}$ .

$\displaystyle \rm -\lambda \cdot (10\;day) = \ln{\left(\frac{\rm 6690\; min^{-1}}{\mathrm{8540\; min^{-1}}}\right)}$ .

$\displaystyle \rm \lambda= \rm \frac{\displaystyle \ln{\left(\frac{\rm 6690\; min^{-1}}{\mathrm{8540\; min^{-1}}}\right)}}{-10 \; day} \approx 0.0200280\; day^{-1}$ .

Note that the unit of the decay constant $\lambda$ is $\rm day^{-1}$ (the reciprocal of days.) The exponent $-\lambda \cdot t$ should be dimensionless. In other words, the unit of $t$ should also be days. This observation confirms that there's no need for unit conversion as long as the two times are in the same unit.

Apply the equation for decay activity at time $t$ to find the decay activity after 47.2 days.

$\displaystyle \begin{aligned}A(t)& = A_0 \cdot \mathrm{e}^{-\lambda\cdot t}\\&\approx \rm \left(8540\; min^{-1}\right)\cdot \mathrm{e}^{-0.0200280\; day^{-1}\times 47.2\;day}\\&\approx \rm 3318\; min^{-1}\end{aligned}$ .

By dimensional analysis, the unit of activity here should also be disintegrations per minute. The activity after 47.2 days will be approximately 3318 disintegrations per minute.

8 0

3 years ago

Electrons are shared. Is it Ionic bond, covalent bond or both?

34kurt

Answer:

covalent bond

Explanation:

ionic bond is when electrons are transferred by atoms not shared

4 0

2 years ago

Hey, please could someone answer this?

pav-90 [236]

Carbon dioxide is the other product created.

5 0

3 years ago

Container A holds 722 mL 722 mL of an ideal gas at 2.40 atm. 2.40 atm. Container B holds 169 mL 169 mL of a different ideal gas

iren [92.7K]

Answer:

The resulting pressure is 2.81 atm

Explanation:

According to Dalton's Law of Partial Pressure, each of the gases (A and B) will exert their pressure independently. If we use Boyle's Law to calculate the pressure of each of the gases separately we have:

Pressure of gas A:

p1V1 = p2V2

p1 = 2.4 atm

V1 = 722 mL

V2 = 722 + 169 = 891 mL

p2 =?

Clearing p2:

p2 = (p1V1)/V2 = (2.4*722)/891 = 1.94 atm

Pressure of gas B:

p1 = 4.6 atm

V1 = 169 mL

V2 = 169+722 = 891 mL

p2=?

Clearing p:

p2 = (4.6*169)/891 = 0.87 atm

Dalton's expression for total partial pressures is equal to:

ptotal = pA + pB = 1.94+0.87 = 2.81 atm

6 0

3 years ago

15. conjugated dienes routinely undergo 1,2 and 1,4 addition reactions with a variety of electrophilic reagents; this suggests t

son4ous [18]

Conjugated dienes routinely undergo 1,2 and 1,4 addition reactions with a variety of electrophilic reagents; this suggests that electrophilic reagents are likely intermediates during these reactions.

Two double bonds and one single bond divide a conjugated diene into two halves. Nonconjugated (Isolated) Dienes have more than one single bond separating two double bonds. Two double bonds are joined to the same atom to form cumulated dienes.

Reagents that function by acquiring electrons or sharing electrons that once belonged to a foreign molecule are referred to as electrophilic reagents, or electrophiles, in some cases. Electrophiles are molecules with a positive charge and a lack of electrons that can react by exchanging electron pairs with nucleophiles, which have many electrons. Epoxides, hydroxy amines, nitroso and azoxy derivatives, nitrenium ions, and elemental sulfur are significant electrophiles.

To know more about Electrophiles refer to: brainly.com/question/21773561

#SPJ4

7 0

2 years ago