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3 years ago

15

a friend is trying to describe a material to you. which of the following is not a description of a physical property of the subs

tance? a. it is red in color. b. it is magnetic. c. when combined with water, it fizzes. d. it melts at 240°c.

2 answers:

jonny [76]3 years ago

5 0

C. when combined with water, it fizzes.

mariarad [96]3 years ago

4 0

When combined with water, it fizzes.

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What type of bond is between sodium and oxygen

Greeley [361]

Answer:

Ionic

Explanation:

Sodium is Metal, Oxygen is Non-metal. Non-metals and metals are automatic Ionic bonds

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3 years ago

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How many liters of oxygen gas, at standard temperature and pressure, will react with 25.0 grams of magnesium metal? Show all of

love history [14]

Given:
2 Mg + O2 → 2 MgO
So,
<span>(25.0 g of Mg / 24.3051 g/mole) x (1/2) x (22.4 L/mole) = 11.5 L of Oxygen will react with 25 grams of magnesium metal.</span>

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3 years ago

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Explain how you would test the presence of oxygen and hydrogen gases.

Vedmedyk [2.9K]

Place a burning splint near the opening of a test tube. If a popping noise occurs, it's probably hydrogen. Place a glowing splint in the test tube, and if it reignites, it could be oxygen. Place a burning splint into a test tube, and if it goes out, it could be carbon dioxide.

5 0

3 years ago

Solid sodium hydrogen carbonate, NaHCO3, decomposes on heating according to the equation:

tekilochka [14]

Answer:

See explanation

Explanation:

First, let's write the balanced equation again:

2 NaHCO3(s) <-> Na2CO3(s) + H2O(g) + CO2(g)

Now, we know that the total pressure was 7.76 atm. This total pressure, is the sum of the pressure of water and CO2 like this:

Ptotal = Pwat + PCO2 (1)

This is the dalton's law for partial pressures.

The pressure can be also be relationed with the moles

Ratio of mole = Ratio of pressure

so, taking this in consideration we can say the following:

Pwater/PCO2 = moles water / moles CO2

As the only components exerting pressure are CO2 and Water (Because they are in gas phase), the total pressure can be splitted between the two of them so:

Pwater = Ptotal/2

Pwater = 7.76 / 2 = 3.88 atm

With this pressure, and using the ideal gas equation, we can know the moles of water:

PV = nRT

n = PV/RT using R = 0.082 L atm / K mol

n = 3.88 * 5 / 0.082 * (160+273)

n = 0.546 moles of water

b) now that we have the moles of water, we can actually know the moles that reacted originally from the sodium carbonate by stechiometry.

2NaHCO3(s) <-> Na2CO3(s) + H2O(g) + CO2(g) MMCO2 = 84 g/mol

the moles of NaHCO3 initially:

n = 100 / 84

n = 1.19 moles

so, If 1.19 moles of NaHCO3 reacted, and only produces 0.546 moles of water and CO2, then, the remaining moles of NaHCO3 is:

remaining moles = 1.19 - 0.546 = 0.644 moles

therefore the mass remaining:

mCO2 = 0.644 * 84

mCO2 = 54.096 g

c) As it was stated before, only the gaseous components are involved in the pressure, thus, in the kp expression which is:

Kp = Pwater * PCO2

Kp = 3.88 * 3.88

Kp = 15.0544

d) As the total pressure is 7.76 atm and the fact that NaHCO3 is solid, this component is not exerting any pressure in the reaction, as seen in the Kp expression, so it won't matter that if we raise a little the quantity of the reactant, it still has some remaining.

3 0

3 years ago

A sample of H2 gas (12.28 g) occupies 100.0 L at 400.0 K and 2.00 atm. A sample weighing 9.49 g occupies ________ L at 353 K and

lutik1710 [3]

Considering the ideal gas law, a sample weighing 9.49 g occupies 68.67 L at 353 K and 2.00 atm.

Ideal gases are a simplification of real gases that is done to study them more easily. It is considered to be formed by point particles, do not interact with each other and move randomly. It is also considered that the molecules of an ideal gas, in themselves, do not occupy any volume.

An ideal gas is characterized by three state variables: absolute pressure (P), volume (V), and absolute temperature (T). The relationship between them constitutes the ideal gas law, an equation that relates the three variables if the amount of substance, number of moles n, remains constant and where R is the molar constant of the gases:

P× V = n× R× T

In this case, you know:

P= 2 atm
V= ?
n= $9.49 gramsx\frac{1 mole}{2 grams} = 4.745moles$ being 2g/mole the molar mass of H2, that is, the amount of mass that a substance contains in one mole.
R= 0.082 $\frac{atmL}{molK}$
T= 353 K

Replacing:

2 atm× V = 4.745 moles× 0.082 $\frac{atmL}{molK}$ × 353 K

Solving:

V = (4.745 moles× 0.082 $\frac{atmL}{molK}$ × 353 K)÷ 2 atm

<u><em>V= 68.67 L</em></u>

Finally, a sample weighing 9.49 g occupies 68.67 L at 353 K and 2.00 atm.

Learn more:

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5 0

2 years ago