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3 years ago

What is the mass of 1.20 x 10^25 atoms of He

Chemistry

1 answer:

AleksandrR [38]3 years ago

4 0

Answer:

79.7 g He

General Formulas and Concepts:

Chemistry - Atomic Structure

Reading a Periodic Table
Using Dimensional Analysis
Avogadro's Number - 6.022 × 10²³ atoms, molecules, formula units, etc.

Explanation:

Step 1: Define

1.20 × 10²⁵ atoms He

Step 2: Identify Conversions

Avogadro's Number

Molar Mass of He - 4.00 g/mol

Step 3: Convert

$1.20 \cdot 10^{25} \ atoms \ He(\frac{1 \ mol \ He}{6.022 \cdot 10^{23} \ atoms \ He} )(\frac{4.00 \ g \ He}{1 \ mol \ He} )$ = 79.7077 g He

Step 4: Check

We are given 3 sig figs. Follow sig fig rules and round.

79.7077 g He ≈ 79.7 g He

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3 years ago

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Makovka662 [10]

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2 years ago

How much time will it take a car traveling at an average of 75 mph to go a distance of 225 miles

mojhsa [17]

Time taken = 3 hours

<h3>Further explanation</h3>

Given

speed : 75 mph

distance : 225 miles

Required

time taken

Solution

An equation of constant velocity motion

$\large {\boxed {\bold {d = v \times \: t}}}$

d = distance = m

v = speed = m / s

t = time = seconds

Input the value :

t = d : v

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2 years ago

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