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3 years ago

What is the mass of an atom that has 4 protons, 5 neutrons, and 4 electrons?

Chemistry

2 answers:

Mazyrski [523]3 years ago

3 0

The answer would be 9

WITCHER [35]3 years ago

3 0

To get the mass, you would add the <span> 4 protons and 5 neutrons so it would be 9.
(The electrons weigh practically nothing so you just ignore them.)</span>

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What is an element considered a pure substance?

Alona [7]

A compound is a pure substance composed of two or more different atoms chemically bonded to one another. A compound can be destroyed by chemical means. It might be broken down into simpler compounds, into its elements or a combination of the two.

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3 years ago

How many liters of 1.5 M HCl solution would react completely with 2.5 moles Ca(OH)2? (2 points)

mylen [45]

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3 years ago

A cube of an unknown metal is 1.25 inches on each side and has a mass of 128.3741 g. What is its' density?

Mademuasel [1]

Hey there!

To find the density of an object, you must use this formula:
Density=Mass/Volume

Knowing that your mass is 128.3741, the only information you need left would be to find the volume of the cube.

Because the side length of the cube is given, you can multiply the length three times in order to find its volume:
1.25*1.25*1.25
=1.953125

Now that you have your volume and mass, divide the mass by the volume to find the density:
128.3741/1.953125
=65.7275392

Therefore, your density would be 65.7275392 grams per inches cubed.

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3 years ago

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3 years ago

3.5g of a Certain compound X, known to be made of carbon, hydrogen, and perhaps oxygen, and to have a molecular molar mass of 15

shutvik [7]

Answer:

C₅H₁₀O₅

Explanation:

1. Calculate the mass of each element in 2.78 mg of X.

(a) Mass of C

$\text{Mass of C} = \text{5.13 g CO}_{2}\times \dfrac{\text{12.01 g C}}{\text{44.01 g }\text{CO}_{2}}= \text{1.400 g C}$

(b) Mass of H

$\text{Mass of H} = \text{2.10 g H$_{2}$O}\times \dfrac{\text{2.016 g H}}{\text{18.02 g H$_{2}$O}} = \text{0.2349 g H}$

(c) Mass of O

Mass of O = 3.5 - 1.400 - 0.2349 = 1.87 g

2. Calculate the moles of each element

$\text{Moles of C = 1400 mg C}\times\dfrac{\text{1 mmol C}}{\text{12.01 mg C }} = \text{116.6 mmol C}\\\\\text{Moles of H = 234.9 mg H} \times \dfrac{\text{1 mmol H}}{\text{1.008 mg H}} = \text{233.1 mmol H}\\\\\text{Moles of O = 1870 mg O} \times \dfrac{\text{1 mmol O}}{\text{16.00 mg O}} = \text{116 mmol O}$

3. Calculate the molar ratios

Divide all moles by the smallest number of moles.

$\text{C: } \dfrac{116.6}{116.6}= 1\\\\\text{H: } \dfrac{233.1}{116.6} = 1.999\\\\\text{O: } \dfrac{116}{116.6} = 1.00$

4. Round the ratios to the nearest integer

C:H:O = 1:2:1

5. Write the empirical formula

The empirical formula is CH₂O.

6. Calculate the molecular formula.

EF Mass = (12.01 + 2.016 + 16.00) u = 30.03 u

The molecular formula is an integral multiple of the empirical formula.

MF = (EF)ₙ

$n = \dfrac{\text{MF Mass}}{\text{EF Mass }} = \dfrac{\text{150 u}}{\text{30.03 u}} = 5.00 \approx 5$

MF = (CH₂O)₅ = C₅H₁₀O₅

The molecular formula of X is C₅H₁₀O₅.

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3 years ago