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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

Chemistry

1 answer:

Soloha48 [4]3 years ago

4 0

N: 106Answer:

72 protons, 106 neutrons, 72 electrons.

Explanation:

to solve this use this simple method: APEMAN.

A= atomic number, P= Protons, E= Electrons.

M= Mass, A= atomic number, N= neutrons.

1. APE (atomic number, protons, electrons) are the same. since Hf (Hafnium) atomic number is 72, Hf has 72 protonsand ele ctrons.

2. to get Neutrons it will be mass-atomic number= neutrons.(M-A=N)

Hf mass= 178. So, 178-72= 106 neutrons.

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Consider the following reaction: NaHCO3 + HC2H3O2 → NaC2H3O2 + H2O + CO2 How many g of CO2 would be produced from the complete r

Alenkasestr [34]

<h2>1.25 g of $CO_2$ would be produced from the complete reaction of 25 mL of 0.833 mol/L $HC_3H_3O_2$ with excess $NaHCO_3$ </h2>

Explanation:

To calculate the number of moles for given molarity, we use the equation:

$\text{Molarity of the solution}=\frac{\text{Moles of solute}\times 1000}{\text{Volume of solution (in L)}}$

$0.833M=\frac{\text{Moles of} HC_3H_3O_2\times 1000}{25ml}\\\\\text{Moles of} HC_3H_3O_2 =\frac{0.833mol/L\times 25}{1000}=0.0208mol$

$NaHCO_3+HC_2H_3O_2\rightarrow NaC_2H_3O_2+H_2O+CO_2$

According to stoichiometry:

1 mole of $HC_2H_3O_2$ will give = 1 mole of $CO_2$

0.0208 moles of $HC_2H_3O_2$ will give = $\frac{1}{1}\times 0.0208=0.0208 moles$ of $CO_2$

Mass of $HC_2H_3O_2=moles\times {\text {molar mass}}=0.0208\times 60g/mol=1.25g$

Thus 1.25 g of $CO_2$ would be produced from the complete reaction of 25 mL of 0.833 mol/L $HC_3H_3O_2$ with excess $NaHCO_3$

Learn more about molarity

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5 0

3 years ago

How many total moles of ions are released when the following sample dissolves completely in water? Enter your answer in scientif

Katena32 [7]

<u>Answer:</u> The number of moles of strontium bicarbonate is $7.5\times 10^{-9}mol$

<u>Explanation:</u>

Formula units are defined as lowest whole number ratio of ions in an ionic compound. It is calculate by multiplying the number of moles by Avogadro's number which is $6.022\times 10^{23}$

We are given:

Number of formula units of $Sr(HCO_3)_2=4.55\times 10^{15}$

As, $6.022\times 10^{23}$ number of formula units are contained in 1 mole of a substance.

So, $4.55\times 10^{15}$ number of formula units will be contained in = $\frac{1}{6.022\times 10^{23}}\times 4.55\times 10^{15}=7.5\times 10^{-9}mol$ of strontium bicarbonate.

Hence, the number of moles of strontium bicarbonate is $7.5\times 10^{-9}mol$

5 0

3 years ago

Identify the chemical reactions as endothermic, exothermic, or neither. An egg cooking: A candle burning: Plaster and water comb

lianna [129]

Answer :

An egg cooking is an endothermic reaction.

A candle burning and Plaster & water combining and becoming warm are exothermic reaction.

Salt being added to water, with no change in temperature neither endothermic nor exothermic reaction.

Explanation :

Endothermic reaction : It is a type of reaction in which energy is absorbed in the form of heat from the surroundings.

Exothermic reaction : It is a type of reaction in which energy is released in the form of heat from the system.

An egg cooking : In this process, the energy is absorbed in the form of heat.

A candle burning and Plaster & water combining and becoming warm : In both the process, the energy is released in the form of heat.

Salt being added to water, with no change in temperature : In this process, neither energy released nor absorbed.

5 0

3 years ago

Read 2 more answers

What can you extract from a refinery

Dmitrij [34]

Answer:

i dont know ask the man behind the man

Explanation:

4 0

3 years ago

Select the following statements that are true. Select all that apply.

geniusboy [140]

Answer:

The statements which are true among these are: (a),(b) and (c) because,

(a) The simplest organic compounds which contains only carbon and hydrogen atoms are called hydrocarbons.

(b) The IUPAC naming of organic compounds have some rules for the naming of compounds, which consists of

Finding the longest chain present in the compound called parent chain.
A prefix for any substituent attach to the parent chain.

And lastly a suffix for the type of bond that molecule have.

(c) Isomers are the compound which same same molecular formula but different arrangement of molecules, due to this different arrangement they have different physical and chemical properties.

4 0

4 years ago