How is the number of moles of an element determined from a known mass?

Chemistry

1 answer:

goblinko [34]4 years ago

4 0

the mass of 1 mole of the element is used as a conversion factor to convert grams to moles

You might be interested in

Calculate the pH in titration of a weak acid: What is the pH in titration of formic acid (HCHO2, 0.200 M, 100.0 mL) after the ad

ki77a [65]

Answer:

pH = 12.61

Explanation:

First of all, we determine, the milimoles of base:

0.120 M = mmoles / 300 mL

mmoles = 300 mL . 0120 M = 36 mmoles

Now, we determine the milimoles of acid:

0.200 M = mmoles / 100 mL

mmoles = 100 mL . 0.200M = 20 mmoles

This is the neutralization:

HCOOH + OH⁻ ⇄ HCOO⁻ + H₂O

20 mmol 36 mmol 20 mmol

16 mmol

We have an excess of OH⁻, the ones from the NaOH and the ones that formed the salt NaHCOO, because this salt has this hydrolisis:

NaHCOO → Na⁺ + HCOO⁻

HCOO⁻ + H₂O ⇄ HCOOH + OH⁻ Kb → Kw / Ka = 5.55×10⁻¹¹

These contribution of OH⁻ to the solution is insignificant because the Kb is very small

So: [OH⁻] = 16 mmol / 400 mL → 0.04 M

- log [OH⁻] = pOH → 1.39

pH = 14 - pOH → 12.61

6 0

3 years ago

Consider the reaction cl2(g) + i2(g) <=> 2 icl(g), which is endothermic as written. what would be the effect on the equili

bogdanovich [222]

The given equilibrium reaction is,

$Cl_{2}(g)+I_{2}(g)+Heat2ICl(g)$

According to Le Chatelier's principle states that when a system in equilibrium is disturbed by varying conditions like concentration, pressure, and temperature of the system, the system tries to counter act the affect by shifting the equilibrium towards the required side.

When $Cl_{2}$ is removed from the system, the concentration of chlorine ( $Cl_{2}$ ) decreases, the equilibrium is disturbed. So, the system tries to re-establish the equilibrium by moving in that direction which produces more of chlorine, that is towards the reactant side.