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3 years ago

Select the correct answer.

Chemistry

2 answers:

timofeeve [1]3 years ago

4 0

Answer:

Explanation:

mario62 [17]3 years ago

3 0

Answer:Answer:

I believe the wavelength is D.

Explanation:

It's the distance from wave to wave, it can be measured from peak to peak.

I hope I helped, please correct me if I'm wrong!

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How many atoms are there in 2.0 moles of magnesium (Mg)?

hjlf

Answer:

It should be 1. 1.2 X 10^24

Explanation:

7 0

2 years ago

ubstance A undergoes a first order reaction A®B with a half-life, t½, of 20 min at 25 °C. If the initial concentration of A in a

Stells [14]

Answer : The concentration of A after 80 min is, 0.100 M

Explanation :

Half-life = 20 min

First we have to calculate the rate constant, we use the formula :

$k=\frac{0.693}{t_{1/2}}$

$k=\frac{0.693}{20\text{ min}}$

$k=3.465\times 10^{-2}\text{ min}^{-1}$

Expression for rate law for first order kinetics is given by:

$t=\frac{2.303}{k}\log\frac{a}{a-x}$

where,

k = rate constant = $3.465\times 10^{-2}\text{ min}^{-1}$

t = time passed by the sample = 80 min

a = initial amount of the reactant = 1.6 M

a - x = amount left after decay process = ?

Now put all the given values in above equation, we get

$80=\frac{2.303}{3.465\times 10^{-2}}\log\frac{1.6}{a-x}$

$a-x=0.100M$

Therefore, the concentration of A after 80 min is, 0.100 M

3 0

2 years ago

Which atom has five electrons in its outer level and 10 electrons in the inner energy levels

Sever21 [200]

Oxygen 47 Hydrogen 63

Silicon 28 Oxygen 25.5

Aluminum 7.9 Carbon 9.5

Iron 4.5 Nitrogen 1.4

Calcium 3.5 Calcium 0.31

Sodium 2.5 Phosphorus 0.22

Potassium 2.5 Chlorine 0.03

Magnesium 2.2 Potassium 0.06

Titanium 0.46 Sulfur 0.05

Hydrogen 0.22 Sodium 0.03

Carbon 0.19 Magnesium 0.01

All others <0.1 All others <0.01 Living matter

6 0

3 years ago

What masses of iron(iii) oxide and aluminum must be used to produce 15.0 g iron? what is the maximum mass of aluminum oxide that

defon

1) Chemical reaction:

Fe2O3 + 2Al ---> Al2O3 + 2Fe

2) molar ratios

1 mol Fe2O3 : 2Al : 1 mol Al2O3 : 2 mol Fe

3) Convert 15.0 g of iron into moles

atomic mass Fe = 55.8 g/mol

moles = mass in grams / atomic mass = 15.0 g / 55.8 g/mol = 0.269 mol

4) Use proportions to determine the moles of Fe2O3, Al, and Al2O3

a) 1mol Fe2O3 / 2 mol Fe = x / 0.269 mol Fe

x =

=> x = 0.269 mol Fe * 1 mol Fe2O3 / 2 mol Fe = 0.134 mol Fe2O3

b) 2 mol Al / 2 mol Fe = x / 0.269 mol Fe

=> x = 0.269 mol Al

c) 2 mol Fe / 1 mol Al2O3 = 0.269 mol Fe / x

=> x = 0.269 mol Fe * 1 mol Al2O3 / 2 mol Fe

x = 0.134 mol Al2O3

5) Convert moles to grams

a) Fe2O3

molar mass Fe2O3 = 2* 55.8 g/mol + 3*16g/mol = 159.6 g/mol

mass = molar mass * number of moles

mass = 159.6 g/mol * 0.134 mol = 21.4 g

b) Al

atomic mass = 27.0 g/mol

mass = number of moles * atomic mass = 0.269 mol * 27.0 g/mol = 7.26 g

c) Al2O3

molar mass = 2 * 27.0 g/mol + 3*16.0 g/mol = 102.0g/mol

mass Al2O3 = numer of moles * molar mass = 0.134 mol * 102.0 g/mol = 13.7 g

Answers:

21.4 g Fe2O3

7.26 g Al

13.7 g Al2O3

6 0

3 years ago

1. Is this equation balanced? Explain your answer. Na + Cl2 → NaCl ?

Delvig [45]

It is not balanced since there are 2 Cl molecules on the left side, and only 1 on the right side. In order to balance this, you would need to make sure there are the same amount of all the molecules on both sides...

4Na + 2Cl2 = 4NaCl

Hope this helps :)

3 0

2 years ago