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3 years ago

14

A balloon containing 0.0400 mol of a gas with a volume of 500 mL was expanded to 1.00 L.

2 answers:

Deffense [45]3 years ago

7 0

Answer:

B and .08 Moles

Explanation:

ANTONII [103]3 years ago

3 0

Answer:

b

Explanation:

answered it correctly

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How many number of moles are present in 200. g of sodium bicarbonate (NaHCO3)

nikdorinn [45]

You can solve this problem through dimensional analysis.

First, find the molar mass of NaHCO3.

Na = 22.99 g

H = 1.008 g

C = 12.01 g

O (3) = 16 (3) g

Now, add them all together, you end with with the molar mass of NaHCO3.

22.99 + 1.008 + 12.01 + 16(3) = 84.008 g NaHCO3. This number means that for every mole of NaHCO3, there is 84.008 g NaHCO3. In simpler terms, 1 mole NaHCO3 = 84.008 g NaHCO3.

After finding the molar mass of sodium bicarbonate, now you can use dimensional analysis to solve for the number of moles present in 200. g of sodium bicarbonate.

$200. g NaHCO_3 * \frac{1 mole NaHCO_3}{84.008 g NaHCO_3}$

Cross out the repeating units which are g NaHCO3, and the remaining unit is mole NaHCO3

200. * 1 = 200

200/ 84.008 = 2.38

Notice how there are only 3 sig figs in the answer. This is because the given problem only gave three sig figs.

Your final answer is 2.38 mol NaHCO3.

8 0

3 years ago

What is the half-life of 20 g of a radioactive sample if 5 g remain after 8 minutes?

Anni [7]

Hello!

The half-life is the time of half-disintegration, it is the time in which half of the atoms of an isotope disintegrate.

We have the following data:

mo (initial mass) = 20 g

m (final mass after time T) = 5 g

x (number of periods elapsed) = ?

P (Half-life) = ? (in minutes)

T (Elapsed time for sample reduction) = 8 minutes

Let's find the number of periods elapsed (x), let us see:

$m = \dfrac{m_o}{2^x}$

$5 = \dfrac{20}{2^x}$

$2^x = \dfrac{20}{5}$

$2^x = 4$

$2^x = 2^2$

$\boxed{x = 2}$

Now, let's find the half-life (P) of the radioactive sample, let's see:

$T = x*P$

$8 = 2*P$

$2\:P = 8$

$P = \dfrac{8}{2}$

$\boxed{\boxed{P = 4\:minutes}}\Longleftarrow(Half-Life)\end{array}}\qquad\checkmark$

I Hope this helps, greetings ... DexteR! =)

5 0

3 years ago

During science, Jim's teacher gives this simple rule to use as a first attempt to increase solubility of the solute and the rate

gladu [14]

B. Agitate the solute in the solvent.

3 0

3 years ago

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A student needed to make 100.0 mL of 0.20M NaOH solution. How many grams of sodium hydroxide does the student need to weigh out

GuDViN [60]

Answer:

0.08 g

Explanation:

100.0 mL = 0.10 L

Multiply the volume by the molarity to find moles.

0.10 L × 0.20 M = 0.002 mol

Convert moles to grams.

0.002 mol × 40 g/mol = 0.08 g

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3 years ago

Explosive volcanic eruptions will hurl: hot cinders volcanic bombs lava pebbles large rocks all of the above

andreev551 [17]

The answer is all of the above

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3 years ago

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