Ask question

Ask question

All categories

3 years ago

15

In Mexico City, what are the two things that are causing most of the pollution? If you answer with an explanation I will give yo

u Brainlist PLEASE HELP ITS DUE IN 30minutes

1 answer:

Andre45 [30]3 years ago

4 0

Tornados and fires burning down houses

You might be interested in

Answer these please.

Crank

Answer:

a) 1.20 × 10²⁴ atoms

b) 10 g

c) 0.7 mol

d) 1,000 g

e) 0.5 mol

f) 3.0 × 10²² atoms

g) 0.20 mol
h) 2.0 mol/dm³
i) 2.8 g

Explanation:

<h2>a) </h2>

1. Data:

Cl: 71g

Ar: Cl 35.5

2. Solution:

i) Formulae:

number of moles = mass in grams/Ar

number of atoms = number of moles × Avogadro constant

Avogadro constant = 6.022 × 10²³ atoms/mol

ii) Calculations:

number of moles = 71g / 35.5(g/mol) = 2 mol

number of atoms = 2mol × 6.022 × 10²³ atoms/mol = 1.20 × 10²⁴ atoms

<h2>b) </h2>

1. Data:

0.2 mol KOH
Ar: H = 1, O = 16, k = 39

2. Solution

i)Formula:

mass = number of moles × molar mass

ii) Molar mass:

1×1g/mol + 1×39g/mol + 1×16g/mol = 56g/mol

iii) Calculations:

mass = 0.2 mol × 56g/mol = 11.2 g/mol ≈ 10g/mol (rounded to 1 significant figure)

<h2>c) </h2>

1. Data:

1.4g Li
Ar: Li = 7

2. Solution

i) Formula:

number of moles = mass in grams / Ar

ii) Calculations:

number of moles = 1.4g / 7 gmol = 0.7 mol

<h2>d) </h2>

1. Data:

S₈
Ar: S = 32

2. Solution

i) Formula:

mass = number of moles × molar mass

ii) Calculations:

molar mass = 8 × 32g/mol = 256 g/mol

mass = 4 mol × 256 g/mol = 1,024 g ≈ 1,000 g (rounded to 1 significant figure)

<h2>e)</h2>

1. Data:

mass: 50 g

Ca(NO₃)₂ . 2H₂O

Mr: Ca(NO₃)₂ . 2H₂O = 200

2. Solution

i) Formulae:

number of moles = mass in grams / molar mass

ii) Calculations:

number of moles = 50 g / 200 g/mol = 0.25 mol of Ca(NO₃)₂ . 2H₂O

The number of moles of water molecules is 2 times the number of moles of Ca(NO₃)₂ . 2H₂O.

number of moles of water molecules = 2 × 0.25 mol = 0.5 mol

<h2>f) </h2>

1. Data:

4.9g

Mr: H₂SO₄ = 98

2. Solution:

i) Formulae:

number of atoms = number of moles × Avogadro constant

number of moles = mass in grams / molar mass

ii) Calculations

number of moles = 4.9g / 98g/mol = 0.050 mol

number of atoms = 0.050 mol × 6.022 × 10²³ atoms/mol = 3.0×10²² atoms

<h2>g) </h2>

1. Data:

V = 24 dm³ (air)
20% oxygen
r.t.p ⇒ T = 298K, p = 1 atm

2. Solution

i) Formula:

pV = nRT

ii) Calculation:

n = (pV)/(RT)

R = 0.08206 (atm.dm³/K.mol)

n = [ 1 atm × 24 dm³] / (0.08206atm.dm³/K.mol × 298K) = 0.98mol of air

moles of oxygen = 20% × 0.98 mol ≈ 0.20 mol

<h2>h) </h2>

1. Data:

V = 125cm³
0.25 mol

2. Solution

i) Formula:

Molarity = moles of solute / volume of solution in dm³

ii) Calculations:

Convert 125 cm³ to liter

25cm³ × (0.1cm/dm)³ = 0.125 dm³

Molarity = 0.25 mol / 0.125 dm³ = 2.0 mol/dm³

<h2>i) </h2>

1. Data:

V = 35cm³
M = 2 mol/dm³
Mr NaOH = 40

2. Solution

i) Formulae:

number of moles = M × V (in dm³)

mass = number of moles × mola rmass

ii) Calculations:

V = 35cm³ × (0.1dm/cm)³ = 0.035dm³

number of moles = 2 mol/dm³ × 0.035 dm³ = 0.070 mol

mass = 0.070 mol × 40 g/mol = 2.8 g

7 0

3 years ago

Elements can be described by various properties, and identified by their boiling and melting points. For example, gold melts at

Leni [432]

Answer:

Elements can be described by various properties, and identified by their boiling and melting points. For example, gold melts at

Elements can be described by various properties, and identified by their boiling and melting points. For example, gold melts at 1,064ºC and boils at 2,856ºC. Does boiling point depend on the mass present?

A. No; chemical properties stay the same regardless of mass.

B. No; physical properties stay the same regardless of mass.

C. Yes; physical properties can change when mass increases or decreases.

D. No; qualitative properties like boiling point stay the same regardless of mass.

Explanation:

3 0

2 years ago

What kind of mixture is a solution? A suspension? A colloid?

hjlf

<span>* The mixture is a type of homogeneous material, whose uniformity is found in any proportion of its constituent substances.

* </span><span>Colloid medium is a type of heterogeneous material, whose diversity is observed only by means of instruments for high resolution.

* </span><span>The suspensions are heterogeneous mixtures containing large and sometimes visible solutes not constituting a homogenous liquid.

hope this helps!</span>

8 0

3 years ago

Read 2 more answers

What is the correct reaction for the dissociation (ionization) for a weak acid?

slava [35]

Answer: HA + H2O ⇌ H3O+ + H- (option #4)

Explanation: Since the acid is weak you have to use a ⇌ (equilibrium) sign. Equilibrium is denoted in a chemical equation by the ⇌ symbol. Also, when any acid dissolves into water, it produces hydronium (H3O+ or H+). Therefore, the fourth chemical reaction is your answer.

7 0

3 years ago

In order for a high temperature boiler or steam engine to produce superheated water, or steam: the heat source must be greater t

Vinil7 [7]

Answer:

the heat source must be greater than 100°C

the water must be permitted to evaporate quickly

the system must be sealed and become pressurized above atmospheric pressure

the vapor pressure must be kept below 760 mmHg

Explanation:

A superheated water is a dry form of steam in which hydrogen bonds that strongly binds the molecules of water has been overcome.

Superheated water finds application in a wide range of places. For example they are used for sterilization of clinical equipment.

To produce steam or superheated water, the temperature of the source must be greater than the boiling temperature and less than the critical temperature at 374°C.
Since superheated water is steam and steam is water in gaseous form. The water must be made to evaporate more quickly than it should condense back.
High pressure and sealing the system helps to produce superheated water very fast.
If the pressure between the vapor is kept low, water will boil faster.

8 0

3 years ago