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3 years ago

An atom of gold (Au) has 79 electrons. How many protons must it have if it has a net charge of 0?

Chemistry

2 answers:

Varvara68 [4.7K]3 years ago

6 0

In order to balance out the Electrons, and give it a net charge of 0, you would need 79 Protons.

RoseWind [281]3 years ago

5 0

Explanation:

It is known that for a neutral atom the number of protons present in that atom is equal to the number of electrons present in it.

Also, atomic number means the sum of total number of protons present in an atom.

For example, when a gold atom has net charge 0 then it means it is neutral in nature.

Also, it contains 79 electrons. This also means it contains 79 protons.

Thus, we can conclude that an atom of gold (Au) which has 79 electrons will also contain 79 protons.

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Determine the number of atoms in 41.0 grams of calcium, Ca. (The mass of one mole of calcium is 40.08 g.)

Dovator [93]

Hi there!

Let me know if you have questions about my answer:

6.15 × 10²⁴

Explanation:

To find the number of atoms, divide the mass of calcium (m) by its molar mass (MM). This will give you the number of moles of calcium (n).

$n = m/MM$ Start with a formula

$=\frac{41.0g}{40.08g/mol}$ Substitute values from the question

$= \frac{41.0g*1mol}{40.08g}$ Simplify

$= \frac{41.0mol}{40.08}$ Cancel out the units "g"

$= 1.022...mol$ Number of moles of calcium, with 4 significant figures

Then, multiply the number of moles of calcium (n) by Avogadro's number ( $N_{A}$ ) to find the number of calcium atoms.

$Number.of.Ca=n*N_{A}$ Start with a formula

$= 1.022mol*\frac{6.022*10^{23}Ca}{1mol}$ Substitute values from the question

$= \frac{1.022mol*6.022*10^{23}Ca}{1mol}$ Simplify

$= 1.022*(6.022*10^{23}Ca)$ Cancel out the units "mol"

$= 6.154*10^{24} Ca$ Multiply, leave one extra digit to help round. "4" tells you to round down.

$= 6.15*10^{24} Ca$ Final answer to 3 significant figures*

*When multiplying and dividing numbers, your final answer will have the same number of significant figures as the number with the least number of significant figures in the question.

40.08 has 4 significant figures. 41.0 has 3 significant figures. So, you want 3 significant figures in your final answer.

I hope this helps!

Learn more about Avogadro's number here:

brainly.com/question/1445383

Check out another answer that uses significant figures:

brainly.com/question/3721164

7 0

3 years ago

. Nhiệt độ ban đầu của 344 g một mẫu sắt là 18,2oC. Nếu mẫu sắt này hấp thụ 2,25 kJ nhiệt lượng thì nhiệt độ cuối của mẫu sắt nà

Mrrafil [7]

Answer:

ano poh paki ult kasi hindi mahintindihan yan question mo hindi mahintindihwn

8 0

2 years ago

Read 2 more answers

You carefully weigh out 11.00 g of caco3 powder and add it to 44.55 g of hcl solution. you notice bubbles as a reaction takes pl

Zinaida [17]

The bubbles that were observed after the mixing of the two substances is one of the products of the reaction. It is the carbon dioxide that is produced. To determine the mass of this gas produced, we need to remember the Law of conservation of mass where mass cannot be created or destroyed. With this, we can say that the total mass that goes in a process should be equal to the mass that is goes out of the process no matter what the reaction is. We do as follows:

Mass of reactants = mass of products
11.00 + 44.55 = 51.04 + mass of carbon dioxide
mass of carbon dioxide = 4.51 g

8 0

3 years ago

A barium hydroxide solution is prepared by dissolving 2.06 g of Ba(OH)2 in water to make 32.9 mL of solution. What is the concen

navik [9.2K]

Answer: 1.36 M

Explanation:

Molarity of a solution is defined as the number of moles of solute dissolved per liter of the solution.

$Molarity=\frac{n\times 1000}{V_s}$

where,

n = moles of solute

To calculate the moles, we use the equation:

moles of solute= $\frac{\text {given mass}}{\text {molar mass}}=\frac{2.06g}{171g/mol}=0.0120moles$

$Molarity=\frac{0.0120\times 1000}{32.9}=0.364M$

The balanced reaction between barium hydroxide and perchloric acid:

$2HCIO_4+Ba(OH_)2\rightarrow BaCIO_4+2H_2O$

To calculate the concentration of acid, we use the equation given by neutralization reaction:

$n_1M_1V_1=n_2M_2V_2$

where,

$n_1,M_1\text{ and }V_1$ are the n-factor, molarity and volume of acid which is $HClO_4$

$n_2,M_2\text{ and }V_2$ are the n-factor, molarity and volume of base which is $Ba(OH)_2$

We are given:

$n_1=1\\M_1=?\\V_1=8.50mL\\n_2=2\\M_2=0.364M\\V_2=15.9mL$

Putting values in above equation, we get:

$1\times M_1\times 8.50=2\times 0.364\times 15.9\\\\M_1=1.36M$

Thus the concentration of the acid is 1.36 M

4 0

3 years ago

The SN1 reaction yields Entry field with incorrect answer two (number) products. This is because ______________________. Entry f

vagabundo [1.1K]

Answer:

Four substitution products are obtained. The carbocation that forms can react with either nucleophile (H2O or CH3OH) from either the top or bottom side of the molecule

Explanation:

An SN1 reaction usually involves the formation of a carbocation in the slow rate determining step. This carbocation is now attacked by a nucleophile in a subsequent fast step to give the desired product.

However, the product is obtained as a racemic mixture because the nucleophile may attack from the top or bottom of the carbocation hence both attacks are equally probable.

The attacking nucleophile in this case may be water or CH3OH

4 0

4 years ago