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3 years ago

why do chemist use relative masses of atoms compared to a refference isotope rather than the actual of the atoms

Chemistry

1 answer:

Maksim231197 [3]3 years ago

5 0

It's as simple as the actual masses of atoms are very small and difficult to work with, that's all.

To expand...

I think logically, it would make sense to use the mass of the individual atoms as your result would be more precise or "true", but practically it would be extraordinarily hard to do.

Relative atomic masses are compared to the Carbon-12 isotope and averaged which is important. The values have been averaged and so in calculations the difference between using relative atomic mass and the actual masses of the atoms will be small. Relative atomic mass accounts for not knowing the mass all atoms as your relative atomic mass is the average mass of the isotopes in a naturally occurring sample of the element, taking into account the proportion of each isotope present.

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How many moles are there in 987 grams of Ra(OH)2? id also love to know the simplest equation for converting moles --> so i co

OlgaM077 [116]

Mole = $\frac{mass}{molar mass}$

Mass of Radium Hydroxide = 987g
Molar Mass of $Ra(OH) _{2}$ = ((226) + (2 * 16) + (2 * 1))
= 260 g / mol

∴ Moles of $Ra(OH) _{2}$ = $\frac{987 g }{ 260 g / mol }$
= 3.796 mols

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2 years ago

What is the unit of measure for energy? watt newtons joules meters per second

egoroff_w [7]

Answer:

c. Joules

Explanation:

I went over this already

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3 years ago

Read 2 more answers

28 ml of 0.10 m hcl is added to 60 ml of 0.10 m sr(oh)2. determine the concentration of oh− in the resulting solution.

Blababa [14]

Here is an acid-base reaction. Hydrochloric acid (HCl) reacts with strontium hydroxide [ Sr(OH)2 ]

Ions H+ and OH- neutralize each other. If the amounts are not equal, one of them will be in excess.
Follow the steps as

1. Find moles of ions: mole= Molarity * Volume (in liter) ; n= M * V OR millimole = Molarity * Volume (in ml) ;
2. Write the equation
3. Find out excess ion
4. Use final volume (V acid + V base ) to calculate concentration of excess ion.

n HCI = 28 ml * 0.10 M = 0.28 mmol, releases 0.28 mmol H+ ions
n Sr(OH)2= 60 ml * 0.10 M= 0.60 mmol, releases 2* 0.60=1.20 mmol OH- ions
since Sr(OH)2⇒ Sr2+ + 2OH-

Neutralization reaction is OH- + H+ ---> H2O. The ratio is 1:1. That means 1 mmol hydroxide ions will neutralize 1 mmol hydrogen ions. Since OH- ions are greater in amount, they will be in excess

n(OH-) - n(H+)= 1.20 - 0.28 = 0.92 mmol OH- ions UNREACTED.

Total volume= V acid + V base= 28 ml + 60 ml = 98 ml

Molarity of OH- ions= mole / Vtotal = 0.92/98= 0.009 M

The answer is 0.009 M.

5 0

3 years ago

Read 2 more answers

Which solution below has the highest concentration of hydroxide ions?a. pH= 3.21b. pH= 7.00c. pH= 7.93d. pH= 12.59e. pH= 9.82

Sloan [31]

Answer:

The solution that has the highest concentration of hydroxide ions is d. pH = 12.59.

Explanation:

You can solve this question using just some chemical facts:

pH is a measure of acidity or alkalinity: the higher the pH the lower the acidity and the higher the alkalinity.
The higher the concentration of hydroxide ions the lower the acidity or the higher the alkalinity of the solution, this is the higher the pH.

Hence, since you are asked to state the solution with the highest concentration of hydroxide ions, you just pick the highest pH. This is the option d, pH = 12.59.

These mathematical relations are used to find the exact concentrations of hydroxide ions:

pH + pOH = 14 ⇒ pOH = 14 - pH

pOH = - log [OH⁻] ⇒ $[OH^-]=10^{-pOH}$

Then, you can follow these calculations:

Solution pH pOH [OH⁻]

a. 3.21 14 - 3.21 = 10.79 antilogarithm of 10.79 = 1.6 × 10⁻¹¹

b. 7.00 14 - 7.00 = 7.00 antilogarithm of 7.00 = 10⁻⁷

c. 7.93 14 - 7.93 = 6.07 antilogarithm of 6.07 = 8.5 × 10⁻⁷

d. 12.59 14 - 12.59 = 1.41 antilogarithm of 1.41 = 0.039

e. 9.82 14 - 9.82 = 4.18 antilogarithm of 4.18 = 6.6 × 10⁻⁵

From which you see that the highest concentration of hydroxide ions is for pH = 12.59.

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2 years ago

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xeze [42]

A hurricane will weaken after making landfall.

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3 years ago