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4 years ago

how many moles of water H2O contain 2.0 x 10^22 molecules of water? express the quantity in moles to two significant figures

1 answer:

7 0

1 mole ------------- 6.02x10²³ molecules
?? moles ---------- 2.0x10²² molecules

( 2.0 x 10²² ) x 1 / 6.02x10²³ => <span>0.0332 moles of water</span>

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If 31.6 g of KMnO4 is dissolved in enough water to give 160 mL of solution, what is the molarity?

Zina [86]

Answer:

A. 1.25M

B. 19.98g

Explanation:

A. Data obtained from the question include the following:

Mass of KMnO4 = 31.6 g

Volume = 160 mL

Molarity =..?

We'll begin by calculating the number of mole KMnO4 in the solution. This is can be obtained as follow:

Mass of KMnO4 = 31.6 g

Molar mass of KMnO4 = 39 + 55 + (16x4) = 158g/mol

Number of mole of KMnO4 =..?

Mole = mass /Molar mass

Number of mole of KMnO4 = 31.6/158 = 0.2 mole

Now, we can obtain the molarity of the solution as follow:

Volume = 160 mL = 160/1000 = 0.16L

Mole of KMnO4 = 0.2 mole

Molarity = mole /Volume

Molarity = 0.2/0.16 = 1.25M

B. Data obtained from the question include the following:

Volume = 300mL

Molarity = 0.74 M

Mass of H2C2O4 =..?

First, we shall determine the number of mole H2C2O4. This is illustrated below:

Volume = 300mL = 300/1000 = 0.3L

Molarity = 0.74 M

Mole of H2C2O4 =?

Mole = Molarity x Volume

Mole of H2C2O4 = 0.74 x 0.3

Mole of H2C2O4 = 0.222 mole

Now, we can easily find the mass of H2C2O4 by converting 0.222 mole to grams as shown below:

Number of mole of H2C2O4 = 0.222 mole

Molar mass of H2C2O4 = (2x1) + (12x2) + (16x4) = 2 + 24 + 64 = 90g/mol

Mass of H2C2O4 =..?

Mass = mole x molar mass

Mass of H2C2O4 = 0.222 x 90

Mass of H2C2O4 = 19.98g

5 0

3 years ago

Which has more kenetic energy: A 150 g bullet fired from a gun achieving a velocity of 440 m/s and a standard baseball weighing

aleksley [76]

Answer:

Bullet has more kinetic energy then baseball.

Explanation:

Mass of the bullet , m = 150 g = 0.150 kg

Velocity of the bullet = v = 440 m/s

Kinetic energy = $\frac{1}{2}\times mass\times (velocity)^2$

Kinetic energy of the bullet = K.E

$K.E=\frac{1}{2}mv^2=\frac{1}{2}\times 0.150 kg\times (440 m/s)^2$

$=14,520 Joules$

Mass of the baseball, m' = $\frac{51}{4} oz$ = 0.36146 kg

(1 ounce = 0.0283495 kg)

Velocity of the baseball= v' = 105.1 mph

1 mile = 1609.34 m

1 hour = 3600 seconds

$v'=\frac{ 105.1\times 1609.34 m}{3600 s}=46.98 m/s$

Kinetic energy of the baseball = K.E'

$K.E'=\frac{1}{2}m'v'^2=\frac{1}{2}\times 0.36146 kg\times (46.98 m/s)^2$

$=398.83 Joules$

14,520 Joules > 398.83 Joules

K.E > K.E'

Bullet has more kinetic energy then baseball.

7 0

4 years ago

HBrO3 <br> A. All non metals “acid subcategory”

Irina-Kira [14]

Non metals acid subcategories

4 0

3 years ago

What is the meaning of the word organism

Lady_Fox [76]

Answer:

B) any complex thing with properties normally associated with living things

5 0

3 years ago

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Explain how the Rutherford gold foil experiment correctly advanced atomic theory away from the plum pudding model?

Rudiy27

Answer is: Rutherford demonstrate that J.J Thompson's Plum Pudding model was not accurate.

Rutherford theorized that atoms have their charge concentrated in a very small nucleus.

This was famous Rutherford's Gold Foil Experiment: he bombarded thin foil of gold with positive alpha particles (helium atom particles, consist of two protons and two neutrons).

Rutherford observed the deflection of alpha particles on the photographic film and notice that most of alpha particles passed straight through foil.

That is different from Plum Pudding model, because it shows that most of the atom is empty space.

7 0

3 years ago

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