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3 years ago

What are three separation techniques to separate iron filings, salt and sand?

1 answer:

8 0

First Magnetic Separation to remove the iron fillings.

Next Dissolution of the sand and salt in water, and Filtration to separate the salt solution from the sand.

Evaporation of the salt solution to get back the salt.

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Need help with 22 and 24

choli [55]

Answer:

22:

Formular:

$atomic \: mass = \frac{ \sum(isotopic \: mass \times \%abundance)}{100} \\$

substitute:

$atomic \: mass = \frac{(23.985 \times 78.70) + (24.986 \times 10.13) + (25.983 \times 11.17)}{100} \\ \\ = \frac{(1887.620) + (253.108) + (290.230)}{100} \\ \\ = \frac{2430.958}{100} \\ \\ { \boxed{ \boxed{average \: atomic \: mass = 24.3 \: amu}}}$

23:

Same element is represented by same number of protons. 

Answer:

6 protons. 6 protons

7 neutrons. 8 neutrons

6 electrons. 6 electrons

Note: Atoms with same proton number but different mass number are called isotopes

5 0

2 years ago

Read 2 more answers

A coffee cup calorimeter will not be used to directly measure the enthalpy of magnesium combustion because

yanalaym [24]

Answer:

A coffee cup calorimeter is great for measuring heat flow in a solution, but it can't be used for reactions that involve gases since they would escape from the cup. The coffee cup calorimeter can't be used for high-temperature reactions, either, because they would melt the cup.

8 0

2 years ago

Read 2 more answers

10) How many grams are there in 1.00 x 10^24 molecules of BC13?

lana66690 [7]

194.5 g of BCl₃ is present in 1 × 10²⁴ molecules of BCl₃.

Explanation:

In order to convert the given number of molecules of BCl₃ to grams, first we have to convert the molecules to moles.

It is known that 1 moles of any element has 6.022×10²³ molecules.

Then 1 molecule will have $\frac{1}{6.022*10^{23} }$ moles.

So $1*10^{24} molecules = \frac{1*10^{24} }{6.022*10^{23} } =1.66 moles$

Thus, 1.66 moles are included in BCl₃.

Then in order to convert it from moles to grams, we have to multiply it with the molecular mass of the compound.

As it is known as 1 mole contains molecular mass of the compound.

As the molecular mass of BCl₃ will be

$Molecular mass of BCl_{3}= Mass of Boron + (3*Mass of chlorine)$

Mass of boron is 10.811 g and the mass of chlorine is 35.453 g.

Molar mass of BCl₃ = 10.811+(3×35.453)=117.17 g.

$grams of BCl_{3}=Molar mass of BCl_{3}*Number of moles$

$grams of BCl_{3}=117.17*1.66=194.5 g$

So, 194.5 g of BCl₃ is present in 1 × 10²⁴ molecules of BCl₃.

3 0

3 years ago

Define Acid dissociation constant constant

stiks02 [169]

Answer:

An acid dissociation constant, K a, (also known as acidity constant, or acid-ionization constant) is a quantitative measure of the strength of an acid in solution. It is the equilibrium constant for a chemical reaction ↽ − − ⇀ − + + known as dissociation in the context of acid–base reactions.

Explanation:

6 0

2 years ago

At 500 K in the presence of a copper surface , ethanoldecomposes according to the equation

klio [65]

Answer:

Explanation:

rate of reaction

= -ve change in pressure of ethanol / time

= - (250 -237 )/100 = - 13 / 100 torr/s

= - 0.13 torr/s

- (237 - 224 )/100 = - 13 / 100 torr/s

= - .13 torr/s

- (224 - 211 )/100 = - 13 / 100 torr/s

= - .13 torr/s

so on

So rate of reaction is constant and it does not depend upon concentration or pressure of reactant .

So order of reaction is zero.

rate of reaction =K [C₂H₅OH]⁰

K is rate constant

K = .13 torr/s

In 900 s decrease in pressure

= 900 x .13 = 117

So after 900s , pressure of ethanol will be

250 - 117 = 133 torr

8 0

2 years ago