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3 years ago

Find the mass of 0.235 moles of SiO2? (NOTE: use correct significant figures!)

Chemistry

1 answer:

marta [7]3 years ago

8 0

Answer: 14.1g

Explanation:

Given that,

number of moles of SiO2 = 0.235 moles

Mass in grams = Z (let unknown value be Z)

Molar mass of SiO2 = ?

To get the molar mass of SiO2, use the atomic mass

Silicon = 28g;

Oxygen = 16g

i.e Molar mass of SiO2 = 28g + (16g x 2)

= 28g + 32g

= 60g/mol

Now, apply the formula

Number of moles = Mass / molar mass

0.235 moles = Z / 60g/mol

Z = 0.235 moles x 60g/mol

Z = 14.1 g

Thus, the mass of SiO2 is 14.1 grams.

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Sodium borohydride, NaBH4, and boron trifluoride, BF3, are compounds of boron. What are the shapes around boron in the borohydri

STatiana [176]

Compound 1: Sodium borohydride
In sodium borohydride (NaBH4), B is a central metal.
Electronic configuration of B is 1s2 2s2 2p1.
B undergoes sp3 hybridization in NaBH4, to generate 4 hybrid orbitals. These hybrid orbitals, forms sigma bond with 4 'H' atoms. Due to this, the structure of sodium borohydride in tetrahedral.
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Compound 2: Boron trifluoride
In boron trifluoride (BF3), B is a central metal.
Electronic configuration of B is 1s2 2s2 2p1.
B undergoes sp2 hybridization in NaBH4, to generate 3 hybrid orbitals. These hybrid orbitals, forms sigma bond with 3 'H' atoms. Due to this, the structure of boron trifluoride is triangular planner.

7 0

3 years ago

Read 2 more answers

An unknown compound with a molar mass of 223.94 g/mol consists of 32.18% c, 4.50% h, and 63.32% cl. find the molecular formula f

Dima020 [189]

The actual number of atoms of each element present in the molecule of the compound is represented by the formula known as molecular formula.

Molar mass of the unknown compound = 223.94 g/mol (given)

Mass of each element present in the unknown compound is determined as:

Mass of carbon, $C$ :

$\frac{32.18}{100}\times 223.94 = 72.06 g$

Mass of hydrogen, $H$ :

$\frac{4.5}{100}\times 223.94 = 10.08 g$

Mass of chlorine, $Cl$ :

$\frac{63.32}{100}\times 223.94 = 141.79 g$

Now, the number of each element in the unknown compound is determined by the formula:

$number of moles = \frac{given mass}{molar mass}$

Number of moles of $C$ :

$number of moles = \frac{72.06}{12} = 6.005 mole\simeq 6 mole$

Number of moles of $H$ :

$number of moles = \frac{10.08}{1} = 10.08 mole\simeq 10 mole$

Number of moles of $Cl$

$number of moles = \frac{141.79}{35.5} = 3.99 mole\simeq 4 mole$

Dividing each mole with the smallest number of mole, to determine the empirical formula:

$C_{\frac{6}{4}}H_{\frac{10}{4}}Cl_{\frac{10}{4}}$

$C_{1.5}H_{2.5}Cl_{1}$

Multiplying with 2 to convert the numbers in formula into a whole number:

So, the empirical formula is $C_{3}H_{5}Cl_{2}$ .

Empirical mass = $12\times 3+1\times 5+2\times 35.5 = 112 g/mol$

In order to determine the molecular formula:

n = $\frac{molar mass}{empirical mass}$

n = $\frac{223.94}{112} = 1.99 \simeq 2$

So, the molecular formula is:

$2\times C_{3}H_{5}Cl_{2} = C_{6}H_{10}Cl_{4}$

6 0

3 years ago

Include two kinds

MatroZZZ [7]

Answer:

Explanation:

Ionic bond:

It is the bond which is formed by the transfer of electron from one atom to the atom of another element.

Both bonded atoms have very large electronegativity difference. The atom with large electronegativity value accept the electron from other with smaller value of electronegativity.

For example:

Sodium chloride is ionic compound. The electronegativity of chlorine is 3.16 and for sodium is 0.93. There is large difference is present. That's why electron from sodium is transfer to the chlorine. Sodium becomes positive and chlorine becomes negative ion. Both atoms are joint together by electrostatic interaction and ionic compound sodium chloride is formed.

Covalent bond:

It is formed by the sharing of electron pair between bonded atoms.

The atom with larger electronegativity attract the electron pair more towards it self and becomes partial negative while the other atom becomes partial positive.

For example:

In water the electronegativity of oxygen is 3.44 and hydrogen is 2.2. That's why electron pair attracted more towards oxygen, thus oxygen becomes partial negative and hydrogen becomes partial positive and both bonded atoms connected together through covalent bond.

8 0

3 years ago

You need to use a dilute hydrochloric acid solution in an experiment. However, the only bottle of hydrochloric acid in your lab’

mr_godi [17]

The pH of the diluted HCl solution is 1.3.

Explanation:

Given:

The concentrated HCl solution of 8.0 M. The 1.5 mL of 8.0 M HCl is diluted with water to 250 mL volume.

To find:

The pH of the diluted HCl solution.

Solution

The concentration of the HCl solution before dilution = $M_1=8.0 M$
The volume of the HCl solution taken for dilution = $V_1=1.5 ml$
The concentration of the HCl solution after dilution = $M_2=?$
The volume of the HCl solution after dilution = $V_2=250 mL$

Using the Dilution equation:

$M_1V_1=M_2V_2\\8.0M\times 1.5ml=M_2\times 250 mL\\M_2=\frac{8.0M\times 1.5ml}{250 mL}=0.048 M$

The concentration of diluted HCl solution = 0.048 M

$HCl(aq)\rightarrow H^+(aq)+Cl^-(aq)$

In the 1 M solution of HCl, there are 1 M of hydrogen ion, then the concentration of hydrogen ions in 0.048 M of HCl will be:

$[H^+]=1\times 0.048M=0.048 M$

The pH of the diluted HCl solution :

$pH=-\log [H^+]\\=-\log [0.048M]=1.18 \approx 1.3$

The pH of the diluted HCl solution is 1.3.

Learn more about the dilution equation here:

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2 years ago

Which molecule has a lewis structure that does not obey the octet rule?

Zepler [3.9K]

I believe a possible Lewis dot structure that does not obey the octet rule, where all elements are required to have 8 electrons in their outermost shell, would be the SF4 molecule.

Sulfur can contain an more than 8 electrons, in this molecule and thus has an expanded octet.

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3 years ago