Math  /  Numbers & Operations

QuestionA thimble of water contains 4.0×10214.0 \times 10^{21} molecules. The number of moles of H2O\mathrm{H}_{2} \mathrm{O} is 6.6×1036.6 \times 10^{-3} 6.6×10236.6 \times 10^{-23} 2.4×10232.4 \times 10^{23} 2.4×10232.4 \times 10^{-23} 2.4×10452.4 \times 10^{45}

Studdy Solution

STEP 1

What is this asking? How many moles of water are there in a thimble if the thimble contains 4.0×10214.0 \times 10^{21} molecules of water? Watch out! Remember Avogadro's number and what it represents!
Don't mix up molecules and moles!

STEP 2

1. Recall Avogadro's Number
2. Calculate the Number of Moles

STEP 3

Avogadro's number, NAN_A, tells us how many particles (like molecules) are in **one mole** of a substance.
It's a **huge** number, approximately 6.022×10236.022 \times 10^{23} particles per mole.
So, if we have one mole of water, we have 6.022×10236.022 \times 10^{23} molecules of water.
Got it?
Super important!

STEP 4

We're given that our thimble has 4.0×10214.0 \times 10^{21} molecules of water.
We want to figure out how many moles this is.
Think of it like this: if Avogadro's number tells us how many molecules are in **one** mole, we can use it to figure out how many moles we have given a certain number of molecules.

STEP 5

To do this, we'll **divide** the number of molecules we have by Avogadro's number.
This is like asking, "How many groups of 6.022×10236.022 \times 10^{23} molecules fit into 4.0×10214.0 \times 10^{21} molecules?" The answer will give us the number of moles.

STEP 6

Let's set up the calculation: Number of Moles=Number of MoleculesNA\text{Number of Moles} = \frac{\text{Number of Molecules}}{N_A}

STEP 7

**Plug in the values:** Number of Moles=4.0×10216.022×1023\text{Number of Moles} = \frac{4.0 \times 10^{21}}{6.022 \times 10^{23}}

STEP 8

Now, let's **crunch the numbers**: Number of Moles4.06.022×102123\text{Number of Moles} \approx \frac{4.0}{6.022} \times 10^{21-23} Number of Moles0.664×102\text{Number of Moles} \approx 0.664 \times 10^{-2}

STEP 9

We can rewrite this in scientific notation as: Number of Moles6.64×103\text{Number of Moles} \approx 6.64 \times 10^{-3} So, our thimble of water contains approximately 6.6×1036.6 \times 10^{-3} moles.
Awesome!

STEP 10

The thimble contains approximately 6.6×1036.6 \times 10^{-3} moles of water.

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