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3 years ago

What are alkali metals

2 answers:

8 0

Alkali metals are any of the elements lithium, sodium, potassium, rubidium, cuisine, and francium, occupying Group 1A (1) of the periodic table. They are very reactive, electropositive, monovalent metals forming strongly alkaline hydroxides.

jeyben [28]3 years ago

7 0

Answer:

Alkali metals are highly reactive elements that appear to be silver and they are found in group 1 of the periodic table. It consists of lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr). As you go further down the group, the more reactive they are. Those elements all react to water and air, so they must be kept in oil to preserve their state.

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1- A sample of gas is in a 3.00 L contain at a pressure of 740.0 mmHg. What is the new pressure of the sample if the container's

inna [77]

Considering the Boyle's law, the new pressure of the sample is 1,776 mmHg.

<h3>What is Boyle's law</h3>

Boyle's law establishes the relationship between the pressure and the volume of a gas when the temperature is constant.

Boyle's law states that the volume occupied by a given mass of gas at constant temperature is inversely proportional to the pressure. This means that if the pressure increases, the volume decreases, while if the pressure decreases, the volume increases.

Boyle's law is expressed mathematically as:

P×V=k

Now it is possible to assume that you have a certain volume of gas V1 which is at a pressure P1 at the beginning of the experiment. If you vary the volume of gas to a new value V2, then the pressure will change to P2, and the following will be true:

P1×V1=P2×V2

<h3>New pressure</h3>

In this case, you know:

P1= 740 mmHg
V1= 3 L
P2= ?
V2= 1.25 L

Replacing in Boyle's law:

740 mmHg× 3 L=P2× 1.25 L

Solving:

P2= (740 mmHg× 3 L) ÷ 1.25 L

P2= 1,776 mmHg

Finally, the new pressure of the sample is 1,776 mmHg.

Learn more about Boyle's law:

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7 0

2 years ago

Read 2 more answers

if the manometer reading is 305 mm and the atmospheric pressure is 1.03 atm, what is the pressure of the gas in the flask?

Leto [7]

We need to make sure that the pressure is in the same units.

let's convert the atm to mmHg. remember that 1 atm= 760 mmHg

1.03 atm (760 mmHg/ 1 atm)= 783 mmHg

to find the pressure of the gas, you just need to subtract the values

pressure of gas= 783 - 305 = 478 mmHg

8 0

4 years ago

Why do we call water the univeral salivnet

ankoles [38]

Water<span> is capable of dissolving a variety of different substances, which is why it is such a good </span>solvent. Water dissolves more than any other liquid, therefor we called it the Universal Solvent.

6 0

3 years ago

A 57.0 mL sample of a 0.120 M potassium sulfate solution is mixed with 35.5 mL of a 0.118 M lead(II) acetate solution and the fo

Katarina [22]

Answer:

Limiting reagent = lead(II) acetate

Theoretical yield = 1.2704 g

% yield = 78.09 %

Explanation:

Considering:

$Molarity=\frac{Moles\ of\ solute}{Volume\ of\ the\ solution}$

Or,

$Moles =Molarity \times {Volume\ of\ the\ solution}$

Given :

For potassium sulfate :

Molarity = 0.120 M

Volume = 57.0 mL

The conversion of mL to L is shown below:

1 mL = 10⁻³ L

Thus, volume = 57.0×10⁻³ L

Thus, moles of potassium sulfate:

$Moles=0.120 M \times {57.0\times 10^{-3}}\ moles$

Moles of potassium sulfate = 0.00684 moles

For lead(II) acetate :

Molarity = 0.118 M

Volume = 35.5 mL

The conversion of mL to L is shown below:

1 mL = 10⁻³ L

Thus, volume = 35.5×10⁻³ L

Thus, moles of lead(II) acetate :

$Moles=0.118 \times {35.5\times 10^{-3}}\ moles$

Moles of lead(II) acetate = 0.004189 moles

According to the given reaction:

$K_2SO_4_{(aq)}+Pb(C_2H_3O_2)_2_{(aq)}\rightarrow 2KC_2H_3O_2_{(s)}+PbSO_4_{(aq)}$

1 mole of potassium sulfate react with 1 mole of lead(II) acetate

0.00684 moles potassium sulfate react with 0.00684 mole of lead(II) acetate

Moles of lead(II) acetate = 0.004189 moles

Limiting reagent is the one which is present in small amount. Thus, lead(II) acetate is limiting reagent. ( 0.004189 < 0.00684)

The formation of the product is governed by the limiting reagent. So,

1 mole of lead(II) acetate gives 1 mole of lead(II) sulfate

0.004189 mole of lead(II) acetate gives 0.004189 mole of lead(II) sulfate

Molar mass of lead(II) sulfate = 303.26 g/mol

Mass of lead(II) sulfate = Moles × Molar mass = 0.004189 × 303.26 g = 1.2704 g

Theoretical yield = 1.2704 g

Given experimental yield = 0.992 g

<u>% yield = (Experimental yield / Theoretical yield) × 100 = (0.992/1.2704 g) × 100 = 78.09 %</u>

3 0

3 years ago

The purpose of the recrystallization step is to aid in the removal of impurities in the crude product. What are the likely ident

Aliun [14]

Answer:

Explanation:

In recrystallization it is important that the solute dissolve in the solvent at higher temperature and the solute should be insoluble in the solvent at lower temperature. It is also important that the impurities dissolves in the solvent at normal room temperature. This is the principle of recrystallization.

The likely identity of the impurities is that it has high solubility in the solvent at lower temperature.

It is necessary to heat the potassium oxalate solution because potassium oxalate will only be soluble in the solvent at higher temperature. Increase in temperature increases solubility.

Placing the solution in an ice bath will make the solution to cool. On cooling sodium oxalate will recrystallize in a purer solid because it is insoluble in the solvent at low temperature leaving behind the impurities in the solution.

5 0

4 years ago