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4 years ago

I really need this fast

Chemistry

2 answers:

Sladkaya [172]4 years ago

8 0

Answer:

drinka jila jokl ruhi

Explanation:

fihk gg secna isla

spayn [35]4 years ago

5 0

Answer:

I think it's me because a ball of golf into some races as it rolls up increases put

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What is the mass of 4.56 moles of copper (ii) fluoride

musickatia [10]

Answer:

463.0 g.

Explanation:

We can use the following relation:

<em>n = mass/molar mass.</em>

where, n is the mass of copper(ii) fluoride (m = 4.56 mol),

mass of copper(ii) fluoride = ??? g.

molar mass of copper(ii) fluoride = 101.543 g/mol.

∴ mass of copper(ii) fluoride = (n)(molar mass) = (4.56 mol)(101.543 g/mol) = 463.0 g.

7 0

3 years ago

Помогите срочно сделать по химии промежуточную отестацию за 8 класс

il63 [147K]

Answer:

This is site for English speakers. Этот сайт на английском, поэтому вопрос могут удалить

Explanation:

1. 2)

2. 3)

3. 4) Sr

4. 3)

5. 4)

6. 2)

7. 1)

8. 4)

9. 3)

10. 3)

11. SO3, H2SO4, Na2SO4

12.

A) оксид меди (II) 2) CuO

Б) хлорид меди(II) 4) CuCl2

В) сульфит меди (II) 3) CuSO 3

Г) гидроксид меди (II) 1) Cu(OH)2

13.

1. Fe+HCl= б) FeCl 2 +H 2

2.Fe+O2= в) Fe 3 O 4

3. Fe(OH) 3 = г)Fe 2 O 3 +H 2O

4. FeCl 2 +NaOH= а) Fe(OH) 2 +NaCl

14. 2Ca + O2 = 2CaO

CaO + H2O = Ca(OH)2

Ca(OH)2 + 2HCl = CaCl2 + 2H2O

6 0

3 years ago

The half-life for beta decay of strontium-90 is 28.8 years. a milk sample is found to contain 10.3 ppm strontium-90. how many ye

ryzh [129]

Answer : The correct answer is 96.68 yrs

Radioactivity Decay :

it is a process in which a nucleus of unstable atom emit energy in form of radiations like alpha particle , beta particle etc .

Radioactive decay follows first order kinetics , so its rate , rate constant , amount o isotopes can be calculated using first order equations .

The first order equation for radioactive decay can be expressed as :

$ln \frac{N}{N_0} = - k*t$ ----------- equation (1)

Where : N = amount of radioisotope after time "t"

N₀ = Initial amount of radioisotope

k = decay constant and t = time

Following steps can be used to find time :

1) To find deacy constant :

Decay constant can be calculated using half life . Decay constant and half life can be related as :

$T _\frac{1}{2} = \frac{ln2}{k}$ ---------equation (2)

Given : Half life of Strontium -90 = 28.8 years

Plugging value of $T_\frac{1}{2}$ in above formula (equation 2) :

$28.8 yrs = \frac{ln 2}{ k }$

Multiply both side by k

$28.8 yrs * k = \frac{ln 2 }{k} * k$

Dividing both side by 28.8 yrs

$\frac{28.8 yrs * k}{28.8 yrs} = \frac{ln 2}{28.8 yrs}$

(ln 2 = 0.693 )

k = 0.0241 yrs⁻¹

Step 2 : To find time :

Given : N₀ = 10.3 ppm N = 1.0 ppm k = 0.0241 yrs⁻¹

Plugging these value in equation (1) as :

$ln (\frac{1.0 ppm}{10.3 ppm} ) = - 0.0241 yrs^-^1 * t$

$ln (0.0971 ) = -0.0241 yrs ^-^1 * t$

(ln 0.0971 = - 2.33 )

Dividing both side by - 0.0241 yrs⁻¹

$\frac{-2.33}{-0.0241 yrs^-^1} = \frac{-0.0241 yrs^-^1 * t}{-0.0241 yrs^-^1}$

t = 96.68 yrs

Hence the concentration of Strontium-90 will drop from 10.3 ppm to 1.0 ppm is 96.68 yrs

3 0

3 years ago

Read 2 more answers

a swimming-pool worker wants the pools pH to be 7.2. She comes by to test the water and finds that the pH is 6.2. What should sh

nikdorinn [45]

Add an alkaline compound to raise the pH to 7.2.

3 0

3 years ago

What is the density of an object that has a volume of 34.2 cm^3 and a mass of 19.6 g? (a) 0.573 g/cm^3 (b) 1.74 g/cm^3 (c) 670 g

KengaRu [80]

Answer: The density of the object will be $0.573g/cm^3$

Explanation:

Density is defined as the mass contained per unit volume.

$Density=\frac{mass}{Volume}$

Given : Mass of object = 19.6 grams

Volume of object= $34.2cm^3$

Putting in the values we get:

$Density=\frac{19.6g}{34.2cm^3}=0.573g/cm^3$

Thus density of the object will be $0.573g/cm^3$

8 0

4 years ago