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3 years ago

What is the [OH-] of a substance that has a pH of 11?

Chemistry

1 answer:

Deffense [45]3 years ago

6 0

Answer:

0.001 M OH-

Explanation:

[OH-] = 10^-pOH, so

pOH + pH = 14 and 14 - pH = pOH

14 - 11 = 3

[OH⁻] = 10⁻³ ; [OH-] = 0.001 M OH-

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Which elements are metalloids? Check all that apply.

Finger [1]

<h3>Answer:</h3>

Boron
Silicon
Tellurium

<h3>Explanation:</h3>

Elements in the periodic table are either metals, non-metals or metalloids.
Metals are elements that react by losing electron(s) to attain an octet configuration. They occupy groups I, II and III of the periodic table and the transition metals.
Non-metals, on the other hand, are elements that react by gaining electron(s) to attain a stable configuration. Examples include halogens and noble gases among others.
Metalloids are elements in the periodic table that have the properties of both metals and non-metals.
Other examples of metalloids are arsenic, tellurium, germanium and polonium.

7 0

3 years ago

Read 2 more answers

1. To identify a diatomic gas (X2), a researcher carried out the following experiment: She weighed an empty 4.8-L bulb, then fil

Delvig [45]

Answer:

1) The diometic gas is N2 (molar mass 28 g/mol)

2) The partialpressure of oxygen is 316.6 mmHg

Explanation:

Step 1: Data given

Volume = 4.8 L

pressure = 1.60 atm

temperature = 30.0°C

Difference in mass after weighting again = 8.7 grams

Step 2:

PV = nRT

⇒ with P = the pressure of the gas = 1.60 atm

⇒ with V = the volume of the gas = 4.8 L

⇒ with n = the number of moles = mass/molar mass

⇒ with R = the gas constant = 0.08206 L*atm/k*mol

⇒ with T = the temperature = 30.0 °C = 303 K

(1.60 atm) (4.8L) = (n)*(0.08206)*(303 K)

n = (1.60 * 4.8) / ( 0.08206*303)

n = 0.30888 mol

Step 3: Calculate molar mass

Molar mass = mass / moles

Molar mass = 8.7 grams / 0.3089 moles

Molar mass ≈ 28 g/mol

The diometic gas is N2

2) What is the partial pressure of oxygen in the mixture if the total pressure is 545mmHg ?

Step 1: Calculate mass of nitrogen

Let's assume a 100 gram sample. This means 38.8 grams is nitrogen

Step2: Calculate moles of N2

Moles N2 = mass N2 / molar mass N2

Moles N2 = 38.8 grams / 28 .02 grams

Moles N2 = 1.38 moles

Step 3: Calculate moles of O2

Moles O2 = (100 - 38.8)/ 32 g/mol

Moles O2 = 1.9125 moles O2

Step 4: Calculate molefraction of oxygen

Molefraction O2 = moles of component/total moles in mixture

=1.9125/(1.9125 + 1.38 moles)

=0.581

Step 5: Calculate the partial pressure of oxygen

PO2 =molefraction O2 * Ptotal

=0.581 * 545mmHg

=316.6 mmHg

The partialpressure of oxygen is 316.6 mmHg

7 0

3 years ago

Balanced Chemical Equation: 2H2(g)+O2(g)——> 2H2O(g)

Tcecarenko [31]

You must use 134 g O₂ to produce 118 g H₂O.

$\%\text{ yield} = \frac{\text{actual yield}}{\text{theoretical yield}} \times 100 \%$

$\text{Theoretical yield} = \text{Actual yield}\times \frac{100\%}{\%\text{ yield}} = \text{118 g }\times \frac{100 \%}{78.2 \%} = \text{150.9 g}$

M_r: 32.00 18.02

2H₂ + O₂ ⟶ 2H₂O

Moles of H₂O = 150.9 g H₂O × (1 mol H₂O/18.02 g H₂O) = 8.374 mol H₂O

Moles of O₂ = 8.374 mol H₂O × (1 mol O₂/2 mol H₂O) = 4.187 mol O₂

Mass of O₂ = 4.1877 mol O₂ × (32.00 g O₂/1 mol O₂) = 134 g O₂

6 0

3 years ago

Red litmus paper explain how it works and how it used

olasank [31]

Answer:

Litmus paper is one type of acid-base indicator. The paper is imbued with dye derived from lichens that change color in response to the presence of an acid or base. ... Red paper is used to detect alkaline pH and will turn a shade of blue in the presence of a basic solution.

8 0

3 years ago

How many molecules of NH3 are produced from 8.01x10-4g of H2

lara31 [8.8K]

Answer:

1.61 x 10²⁰ molecules

Explanation:

Given parameters:

Mass of the hydrogen gas = 8.01 x 10⁻⁴g

Unknown

Number of molecules of NH₃ = ?

Solution:

Given reaction:

N₂ + 3H₂ → 2NH₃

We have to solve from the known to the unknown

The known specie is the mass of H₂ ;

find the number of moles of the specie;

number of moles = $\frac{mass}{molar mass}$

Molar mass of H₂ = 2(1) = 2g/mol

Number of moles = $\frac{0.0008}{2}$ = 0.0004mol

3 moles of H₂ will produce 2 moles of NH₃

0.0004 moles of H₂ will produce $\frac{0.0004 x 2}{3}$ = 0.00027moles of NH₃

1 mole of a substance contains 6.02 x 10²³ molecules

0.00027mole of NH₃ will contain 0.00027 x 6.02 x 10²³

= 1.61 x 10²⁰ molecules

4 0

3 years ago