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Mnenie [13.5K]
3 years ago
9

Half life in chemistry I wasn't here when we did this

Chemistry
1 answer:
tatuchka [14]3 years ago
6 0
A half-life is the amount of time it takes for half of a substance to decay.

1.) After one half-life - 13.5mg.
After two - 6.75mg
Three - 3.375mg

2.) 250mg of Iron-59 will remain.

3.) 14 days is the half-life of Phospherous-32.
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For each of the following sublevels, give the n and l values and the number of orbitals: (a) 5s; (b) 3p; (c) 4f
OverLord2011 [107]

Answer:

(a) 5s. n = 5. Sublevel s, l = 0. Number of orbitals = 1

(b) 3p. n = 3. Sublevel p, l = 1. Number of orbitals = 3

(c) 4f. n =4. Sublevel f, l = 3. Number of orbitals = 7

Explanation:

The rules for electron quantum numbers are:

1. Shell number, 1 ≤ n

2. Sublevel number, 0 ≤ l ≤ n − 1

So,

(a) 5s. n = 5, shell number 5. Sublevel s, l = 0. Number of orbitals = 2l +1 = 1

(b) 3p. n = 3, shell number 3. Sublevel p, l = 1. Number of orbitals = 2l +1 = 3

(c) 4f. n =4, shell number 4. Sublevel f, l = 3. Number of orbitals =  2l +1 = 7

6 0
3 years ago
A 7.5 L cylinder contains 5 moles of gas at a temperature of 274°C. What is its pressure in kiloPascals (kPa)?
AleksAgata [21]
<h3><u>Answer;</u></h3>

 = 3032.15 kPa

<h3><u>Explanation;</u></h3>

Using the equation;

PV = nRT , where P is the pressure,. V is the volume, n is the number of moles and T is the temperature and R is the gas constant, 0.08206 L. atm. mol−1.

Volume = 7.5 L, T = 274 +273 = 547 K, N = 5 moles

Therefore;

Pressure = nRT/V

               = (5 × 0.08206 × 547)/7.5 L

               = 29.925 atm

But; 1 atm = 101325 pascals

Hence; Pressure = 3032150.63 pascals

                            <u>= 3032.15 kPa</u>

               

3 0
3 years ago
The diagram shows an electric generator connected to a lightbulb. Not all of
BaLLatris [955]

Answer:

The lightbulb transforms it into thermal energy.

Explanation:

5 0
3 years ago
Calculate the molarity of the acid solution.<br>H2SO4(aq) with a pH of 2.
Lena [83]

Concentration "molarity" of H₂SO₄ in this solution:

5 × 10⁻³ mol / dm³.

<h3>Explanation</h3>

What's the concentration of H⁺ ions in this solution?

[\text{H}^{+}] = 10^{-\text{pH}},

where [\text{H}^{+}] is in the unit mol / dm³.

\text{pH} = 2

[\text{H}^{+}] = 10^{-2} \;\text{mol}\cdot\text{dm}^{-3}.

What's the concentration "molarity" of H₂SO₄ in this solution?

Sulfuric acid H₂SO₄ is a strong acid. Note the subscript "2". Each mole of this acid dissolves in water to produce two moles of H⁺ ions. It takes only \dfrac{10^{-2}}{2} = 5 \times 10^{-3}\;\text{mol}\cdot\text{dm}^{-3} of H₂SO₄ to produce twice as much H⁺ ions.

As a result, the <em>molarity</em> of H₂SO₄ is 5 × 10⁻³ mol / dm³ or 0.005 M.

3 0
3 years ago
NEED HELP ASAP!!!!! PLEASE HELP!!!!! NEED HELP ASAP!!!!!
r-ruslan [8.4K]

Answer:

CH4 - Methane

B2Si - Diboron monosilicide

N2O5 - Dinitrogen pentoxide

CO2 - Carbon dioxide

Explanation:

When it comes to naming covalent compounds, there are several rules.

The name is derived based on the formula. For example, N2O5. The first element is nitrogen. To the name of the element, you add the prefix that tells us how many of its atoms are in the compound. In this case, there are two atoms, which means that the prefix will be <em>di</em>- (dinitrogen). The second element is oxygen. You are supposed to take only the root of the second element's name and then add the prefix denoting the number of its atoms and the suffix <em>-ide</em> (pentoxide). This is how we'll get dinitrogen pentoxide.

The only exception is methane (CH4), which is an organic compound. Organic compounds are named using the IUPAC nomenclature.

3 0
3 years ago
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