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3 years ago

How many protons, neutrons, and electrons are present in an atom of hafnium, Hf, with a mass number of 178?

1 answer:

6 0

Answer:Hafnium is a chemical element with atomic number 72 which means there are 72 protons and 72 electrons in the atomic structure. The chemical symbol for Hafnium is Hf. Neutron Number and Mass Number of Hafnium Mass numbers of typical isotopes of Hafnium are 176-178, 179, 180.

Explanation:

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18 An important environmental consideration is the appropriate disposal of cleaning solvents. An environmental waste treatment c

Katyanochek1 [597]

Answer:

a) Percentage by mass of carbon: 18.3%

Percentage by mass of hydrogen: 0.77%

b) Percentage by mass of chlorine: 80.37%

c) Molecular formula: $C_{2} H Cl_{3}$

Explanation:

Firstly, the mass of carbon must be determined by using a conversion factor:

$0.872g CO _{2} *\frac{12g C}{44g CO_{2} } = 0.238g CO_{2}$

The same process is used to calculate the amount of hydrogen:

$0.089g H_{2}O*\frac{2g H}{18g H_{2}O } = 0.010g H$

The percentage by mass of carbon and hydrogen are calculated as follows:

%C $\frac{0.238g}{1.3g} *100%$ = 18.3%

%H $\frac{0.010g}{1.3g} *100%$ =0.77%

From the precipation data it is possible obtain the amount of chlorine present in the compound:

$1.75 AgCl*\frac{35.45g Cl}{143.45g AgCl}$ = 0.43g AgCl

Let's calculate the percentage by mass of chlorine:

%Cl= $\frac{0.43g}{0.535g} * 100%$ = 80.37%

Assuming that we have 100g of the compound, it is possible to determine the number of moles of each element in the compound:

$18.3g C*\frac{1mol C}{12g C} = 1.52mol C$

$0.77g H*\frac{1mol H}{1g H} = 0.77mol H$

$80.37gCl*\frac{1molCl}{35.45g Cl} = 2.27mol Cl$

Dividing each of the quantities above by the smallest (0.77mol), the subscripts in a tentative formula would be

$C=\frac{1.52}{0.77} = 1.97$ ≈ 2

$H = \frac{0.77}{0.77} = 1$

$Cl =\frac{2.27}{0.77}=2.94$ ≈3

The empirical formula for the compound is:

$C_{2} H Cl_{3}$

The mass of this empirical formula is:

mass of C + mass of H + mass of Cl= 24g +1+ 106.35 =131.35g

This mass matches with the molar mass, which means that the supscript in the molecular formula are the same of the empirical one.

5 0

3 years ago

CLIOT

zhuklara [117]

The many electron diamonds around the central carbon are 1689

6 0

3 years ago

2. All metals are good conductors because their electrons can

dsp73

Answer: An insulator would be made out of material unable to conduct electricity due to lack of fluid movement for electrons, such as rubber. Rubber properties not only prevents them from freely moving, but also helps electrons stay tightly bound to each other.

Hope this helps ^_^

4 0

3 years ago

Suppose that 4.8 L of methane at a pressure

Ghella [55]

Answer:

972.3 Torr

Explanation:

P2=P1V1/V2

You can check this by knowing that P and V at constant T have an an inverse relationship. Hence, this is correct.

6 0

3 years ago

John is carefully pouring a chemical into a beaker when the beaker slips and breaks

Kryger [21]

Following laboratory safety protocols such as wearing personal protective equipment will protect John when the accident occurred.

<h3>What are laboratory safety protocols?</h3>

Laboratory safety protocols are the protocols put in place to ensure safety in the laboratory.

Laboratory safety protocols include the following:

always wear personal protective equipment in the laboratory
do not play in the laboratory
do not eat in the laboratory

Following laboratory safety protocols will help protect us from accidents which occur in the laboratory.

What happened when john was carefully pouring a chemical into a beaker when the beaker slips and breaks is an example of laboratory accident.

Wearing personal protective equipment will protect John.

In conclusion, following laboratory safety protocols will protect us when accidents occur in the laboratory.

Learn more about laboratory safety protocols at: brainly.com/question/17994387

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Note that the complete question is given as follows:

John is carefully pouring a chemical into a beaker when the beaker slips and breaks. How would laboratory safety protocols help John?

5 0

2 years ago