Which statement describes an element?

Arrange the following aqueous solutions in order of decreasing freezing point: 0.10 m Na3PO4, 0.35 m NaCl, 0.20 m MgCl2, 0.15 m

GarryVolchara [31]

Answer: 0.35 m $NaCl$ > 0.20 m $MgCl_2$ >0.10 m $Na3PO_4$ > 0.15 m $CH_3COOH$ > 0.15 m $C_6H_{12}O_6$

Explanation:

Depression in freezing point:

$T_f^0-T_f=i\times k_b\times m$

where,

$T_f$ = freezing point of solution

$T^o_f$ = freezing point of solvent

$k_f$ = freezing point constant

m = molality

1. For 0.10 m $Na3PO_4$

$Na_3PO_4\rightarrow 3Na^++PO_4^{3-}$

, i= 4 as it is a electrolyte and dissociate to give 4 ions. and concentration of ions will be $4\times 0.10=0.40$

2. For 0.35 m $NaCl$

$NaCl\rightarrow Na^++Cl^-$

, i= 2 as it is a electrolyte and dissociate to give 2 ions. and concentration of ions will be $2\times 0.35=0.70$

3. For 0.20 m $MgCl_2$

$MgCl_2\rightarrow Mg^{2+}+2Cl^-$

, i= 3 as it is a electrolyte and dissociate to give 3 ions. and concentration of ions will be $3\times 0.20=0.60$

4. For 0.15 m $C_6H_{12}O_6$

, i= 1 as it is a non electrolyte and does not dissociate to give ions.

5. For 0.15 m $CH_3COOH$

$CH_3COOH\rightarrow CH_3COO^-+H^+$

, i= 2 as it is a electrolyte and dissociate to give 2 ions and thus have $2\times 0.15=0.30$

As concentration is highest for 0.35 m $NaCl$ , freezing point depression will be highest and thus has lowest freezing point. As concentration is lowest for 0.15 m $C_6H_{12}O_6$ , freezing point depression will be lowest and thus has highest freezing point

8 0

3 years ago

What are the symbols, atomic mass and abundance in nature of the isotope boron-11

Aneli [31]

The chemical symbol of the isotope boron-11 is ¹¹B.
The atomic mass of the isotope boron-11 is equal to 11.009306.
The abundance in nature of the isotope boron-11 is equal to 80.1%.

<h3>What is an isotope?</h3>

An isotope can be defined as the atom of a chemical element that has the same number of protons but different number of neutrons. This ultimately implies that, the isotopes of an element have the same atomic number (number of protons) but different atomic mass (number of neutrons).

In Chemistry, there are two main isotopes of boron and these include the following:

Boron-10

Boron-11

Boron-11 is the most stable isotope of boron and it is characterized by the following:

The chemical symbol of the isotope boron-11 is ¹¹B.
The atomic mass of the isotope boron-11 is equal to 11.009306.
The abundance in nature of the isotope boron-11 is equal to 80.1%.

Read more on Boron-11 here: brainly.com/question/6283234

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8 0

2 years ago

In the reaction, Zn(s) + 2 HCl(aq) --> ZnCl2 (aq)+ H2(g), 25 grams of Zn are reacted with 17.5 g of HCl. How many grams of H2

Gennadij [26K]

Answer:

0.480 g of H₂ are produced, in the reaction.

Explanation:

This is the reaction:

Zn(s) + 2HCl → ZnCl₂ (aq) + H₂ (g)

We havethe mass of both reactants, so we must work with them to find out the limiting reactant and then, determine the amount of H₂ produced.

Let's convert the mass to moles ( mass / molar mass)

25 g / 65.41 g/mol = 0.382 moles Zn

17.5 g / 36.45 g/mol = 0.480 moles HCl

Ratio is 1:2, so 1 mol of Zn react with the double of moles of HCl.

0.382 moles of Zn would need the double of moles to react, so (0.382 .2) = 0.764 moles of HCl. → We only have 0.480 moles, so the acid is the limiting.

Now let's determine the moles of H₂ formed.

Ratio is 2:1, so If i take account the moles I have, I will produce the half of moles of my product.

0.480 moles / 2 = 0.240 moles of H₂ are produced.

To find out the mass, we must multiply mol . molar mass

0.240 mol . 2g/mol = 0.480 g

3 0

3 years ago

B) Name three substances which can undergo sublimation and deposition respectively

SpyIntel [72]

solid carbon dioxide, iodine, arsenic, and naphthalene

Explanation:

Examples of substances that undergo sublimation

Examples of solids that sublime are dry ice (solid carbon dioxide), iodine, arsenic, and naphthalene (the stuff mothballs are made of).

3 0

3 years ago

What is the effect on pollution when cool air becomes trapped under warm air?

sergejj [24]

More pollutants accumulate

3 0

3 years ago

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