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2 years ago

I need help I have to pass to graduate

Chemistry

1 answer:

andreev551 [17]2 years ago

5 0

I don’t know off the top of my head but just look at a periodic table (most elements are metal anyway)

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In which state of matter are the particles least able to move?

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The solid state where particles are more compact

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3 years ago

Use the words protons neutrons and I suppose in the same sentence

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Isotopes have the same number of protons but a different number of neutrons.

Explanation:

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What element is located in group 2, period 2?

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3 years ago

What is the volume of 4.78g of O2 gas at STP?

My name is Ann [436]

Answer:

Explanation:

The trick here is to realize that if you know the volume of a gas at STP, you can use the fact that

mole of any ideal gas occupies

22.7 L

under STP conditions to calculate how many moles of gas you have in your sample.

Under STP conditions:

1 mole of an ideal gas = 22.7 L

−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−

In your case, you know that your sample of gas occupies

2.28 L

under STP conditions, which are currently defined as a pressure of

100 kPa

and a temperature of

∘

This means that your sample will contain

2.28

⋅

molar volume of a gas at STP



1 mole gas

22.7

0.10044 moles gas

Now, the molar mass of the gas is the mass of exactly

mole of the gas. In your case, you know that you get

3.78 g

for every

0.10044

moles, which means that you have

mole

⋅

3.78 g

0.10044

moles

37.6 g

Since this is the mass of

mole of gas, you can say that the molar mass of the gas is

molar mass = 37.6 g mol

−

−−−−−−−−−−−−−−−−−−−−−−−

8 0

2 years ago

Read 2 more answers

Following the instructions in your lab manual, you have titrated a 25.00 mL sample of 0.0100 M KIO3 with a solution of Na2S2O3 o

vivado [14]

Answer:

For 1: The amount of potassium iodate that were titrated is $2.5\times 10^{-4}$ moles

For 2: The amount of sodium thiosulfate required is $1.25\times 10^{-4}$ moles

Explanation:

For 1:

To calculate the number of moles for given molarity, we use the equation:

$\text{Molarity of the solution}=\frac{\text{Moles of solute}\times 1000}{\text{Volume of solution (in L)}}$

Molarity of $KIO_3$ solution = 0.0100 M

Volume of solution = 25 mL

Putting values in above equation, we get:

$0.0100M=\frac{\text{Moles of }KIO_3\times 1000}{25}\\\\\text{Moles of }KIO_3=\frac{0.0100\times 25}{1000}=0.00025mol$

Hence, the amount of potassium iodate that were titrated is $2.5\times 10^{-4}$ moles

For 2:

The chemical equation for the reaction of potassium iodate and sodium thiosulfate follows:

$2KIO_3+Na_2S_2O_3\rightarrow K_2S_2O_3+2NaIO_3$

By Stoichiometry of the reaction:

2 moles of potassium iodate reacts with 1 mole of sodium thiosulfate

So, 0.00025 moles of potassium iodate will react with = $\frac{1}{2}\times 0.00025=0.000125mol$ of sodium thiosulfate

Hence, the amount of sodium thiosulfate required is $1.25\times 10^{-4}$ moles

6 0

2 years ago