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egoroff_w [7]
2 years ago
15

Timmy and his dad are throwing rocks into the pond. The rocks that Timmy's dad throws go farther and faster. Which of

Chemistry
1 answer:
7nadin3 [17]2 years ago
3 0
Can you put a picture
You might be interested in
How many atoms are in 25.00 g of B?
klio [65]

Answer:

There are 1.393 x 10²⁴ atoms in 25.00 g of B.

Explanation:

Hey there!

We are given a value, in grams, that we need to convert to a number of atoms.

We can convert grams to atoms by using Avogadro's Number (N_A). This number is equivalent to 6.022 \times 10^{23}.

This number can be used to convert any values to:

  • atoms
  • molecules
  • formula units
  • moles

In order to do this problem, we will need to use dimensional analysis (DA). This process allows us to convert from grams to atoms.

We need to set up our ratios in order to work this out. We can use a periodic table to help us through this next part of the problem.

<u>1. Locating the number of moles of B in the sample</u>

We first need to find the amount of moles of boron (B) there are in the sample.

Checking a periodic table, the atomic mass in atomic mass units (amu) is 10.81 amu.

  • Atomic mass units can easily be converted to grams and these units can be used interchangeably.

Therefore, for each atom of boron, it weighs 10.81 grams to us. This is equivalent to the mass of one mole of boron.

To find the number of moles, we have two possible ratios we can use:

  • \displaystyle \frac{1 \ mole \ B}{10.81 \ grams \ B}
  • \displaystyle \frac{10.81 \ grams \ B}{1 \ mole \ B}

These ratios mean the same thing, but we need to convert our final unit to moles.

We are given a sample in grams, and when dividing our units, we need to keep moles.

Since the first portion of our expression is in grams, we need to have grams in the bottom of our expression.

  • \displaystyle 25.00 \ \text{grams B} \ \times \frac{1 \text{mole B}}{10.81 \ \text{grams B}}

We can now simplify the expression. Our <u>grams B</u> unit will cancel out, so we are therefore left with <u>moles B</u> remaining.

<u>2. Locating the number of atoms in the sample</u>

Now with our equation, we can convert our number of moles that would be solved if we stopped with the above. However, we need to convert to atoms.

We use Avogadro's number and create a ratio with that of moles.

  • \displaystyle \frac{6.022 \times 10^{23}\text{atoms}}{1 \text{mole B}}
  • \displaystyle \frac{1 \text{mole B}}{6.022 \times 10^{23} \text{atoms}}

We need to cancel out our moles and end with atoms, so we must have moles in the denominator. Therefore, we use the first ratio.

Using our previous expression, we multiply by this new ratio and solve the expression.

  • \displaystyle 25.00 \ \text{grams B} \ \times \frac{1 \text{mole B}}{10.81 \ \text{grams B}} \ \times \frac{6.022 \times 10^{23}\text{atoms}}{1 \text{mole B}}

This expression can now be operated. You will need a calculator to perform this calculation.

<u>Our numerator is:</u>

  • [(25.00 \times 1 \times (6.022 \times 10^{23})]

Plugging this into a calculator, we get:

  • 1.5055 \times 10^{25}

<u>Our denominator is:</u>

  • (1 \times 10.81 \times 1)

This simplifies to:

  • 10.81

<u>Dividing our numerator and denominator:</u>

  • <u />\displaystyle \frac{1.5055 \times 10^{25}}{10.81}<u />

Plugging this into a calculator, we get:

  • 1.392691952 \times 10^{24}

<u>3. Simplifying with significant figures</u>

Now, we need to take into account that we have significant figures. We are given this original value:

  • 25.00

This value has four significant figures, which means we need to round our value we received above to four significant figures.

  • \approx 1.393

Our units are added as well as our scientific notation:

  • 1.393 \times 10^{24} \ \text{atoms of B}

Therefore, our final answer is choice A.

8 0
2 years ago
A student dissolves 0.0688 mol of sodium hydroxide in water to make a 0.250 L solution. What is the molarity of the solution?
den301095 [7]
Number of moles = 0.0688 moles of NaoH

volume = 0.250 L

Molarity = moles of solute / volume ( L )

M = 0.0688 / 0.250

M = 0.28 M

Answer B
7 0
3 years ago
What is the strong nuclear force
Arturiano [62]

Answer:

A fundamental interaction of nature that acts between subatomic particles of matter. The strong force binds quarks together in clusters to make more-familiar subatomic particles, such as protons and neutrons. Something like that.

Explanation:

8 0
3 years ago
In 1676, Robert Plot discovered a large bone in a quarry in Cornwall, England. He observed that the bone looked similar to a hum
sergeinik [125]

Answer:

D

Explanation:

4 0
3 years ago
Describe what is happening to the mass of water when sugar is dissolved in it.(5 sentences min) ​
nika2105 [10]

Answer:​

The solid sugar crystals break apart in water as the sugar dissolves, but the individual sugar particles or molecules are still present and do not change as a result of dissolving in the water. The combined mass of the sugar and water shouldn't change.

Explanation:

4 0
2 years ago
Read 2 more answers
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