1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Aleks [24]
3 years ago
14

How many moles of sand (SiO2) are in 30 g of sand?

Chemistry
2 answers:
luda_lava [24]3 years ago
6 0

Answer:

\boxed {\boxed {\sf About \ 0.5 \ moles \ of \ SiO_2}}

Explanation:

To convert from grams to moles, we must use the molar mass.

<u>1. Molar Mass </u>

Use the Periodic Table to find the masses of the individual elements (silicon and oxygen) in sand.

  • Silicon (Si): 28.085 g/mol
  • Oxygen (O): 15.999 g/mol

Examine the formula for sand: SiO₂. There is a subscript of 2 after oxygen, so there must be 2 oxygen atoms. Multiply oxygen's mass by 2 and add silicon's mass to find the molar mass of sand.

  • SiO₂: 2(15.999 g/mol) + 28.085 g/mol= g/mol

<u>2. Calculate Moles </u>

Use the molar mass as ratio.

\frac{60.083 \ g \ SiO_2}{1 \ mol \ SiO_2}

Multiply by the given number of grams (30)

30 \ g \ SiO_2 *   \frac{60.083 \ g \ SiO_2}{1 \ mol \ SiO_2}

Flip the fraction so the grams of sand will cancel.

30 \ g \ SiO_2 *\frac{1 \ mol \ SiO_2}{60.083 \ g \ SiO_2}

30  *\frac{1 \ mol \ SiO_2}{60.083 }

\frac{30 \ mol \ SiO_2}{60.083 }

0.499309289 \ mol \ SiO_2

<u>3. Round </u>

The original measurement of grams has 1 signfiicant figure. We must round our answer to 1 sig fig.

For the answer we found, that is the tenth place. The 9 in the hundredth tells us to round the 4 to a 5.

\approx 0.5 \ mol \ SiO_2

There are about <u>0.5 moles</u> of SiO₂ in 30 grams.

anastassius [24]3 years ago
5 0
<h3>Answer:</h3>

0.50 mol SiO₂

<h3>General Formulas and Concepts:</h3>

<u>Math</u>

<u>Pre-Algebra</u>

Order of Operations: BPEMDAS

  1. Brackets
  2. Parenthesis
  3. Exponents
  4. Multiplication
  5. Division
  6. Addition
  7. Subtraction
  • Left to Right

<u>Chemistry</u>

<u>Atomic Structure</u>

  • Reading a Periodic Table
  • Using Dimensional Analysis
<h3>Explanation:</h3>

<u>Step 1: Define</u>

30 g SiO₂ (sand)

<u>Step 2: Identify Conversions</u>

Molar Mass of Si - 28.09 g/mol

Molar Mass of O - 16.00 g/mol

Molar Mass of SiO₂ - 28.09 + 2(16.00) = 60.09 g/mol

<u>Step 3: Convert</u>

  1. Set up:                                \displaystyle 30 \ g \ SiO_2(\frac{1 \ mol \ SiO_2}{60.09 \ g \ SiO_2})
  2. Multiply/Divide:                  \displaystyle 0.499251 \ mol \ SiO_2

<u>Step 4: Check</u>

<em>Follow sig figs and round. We are given 2 sig figs.</em>

0.499251 mol SiO₂ ≈ 0.50 mol SiO₂

You might be interested in
<img src="https://tex.z-dn.net/?f=%5Chuge%7B%5Cboxed%7B%5Cmathfrak%7BQuestion%3A%7D%7D%7D%5C%20%20%5Ctextless%20%5C%20br%20%2F%5
Kisachek [45]

Explanation:

when hot copper metal reacts with chlorine gas it forms CuCl2 which is yellow in colour.

non metal carbon burns in Oxygen gas they form non metal oxide.

5 0
3 years ago
Read 2 more answers
ASPA!!!! How could a scientist determine what elements are present in a distant star by looking at its absorption spectrum?
8_murik_8 [283]

Answer:

Spectroscopy

Explanation:

They can determine its composition based on these wavelengths. The most common method astronomers use to determine the composition of stars, planets, and other objects is spectroscopy

8 0
2 years ago
(3) A 10.00-mL sample of 0.1000 M KH2PO4 was titrated with 0.1000 M HCl Ka for phosphoric acid (H3PO4): Ka1= 7.50x10-3; Ka2=6.20
shtirl [24]

Answer:

The pH of this solution is 1,350

Explanation:

The phosphoric acid (H₃PO₄) has three acid dissociation constants:

HPO₄²⁻ ⇄ PO4³⁻ + H⁺        Kₐ₃ = 4,20x10⁻¹⁰  (1)

H₂PO₄⁻ ⇄ HPO4²⁻ + H⁺    Kₐ₂ = 6,20x10⁻⁸   (2)

H₃PO₄ ⇄ H₂PO4⁻ + H⁺       Kₐ₁ = 7,50x10⁻³   (3)

The problem says that you have 10,00 mL of KH₂PO₄ (It means H₂PO₄⁻) 0,1000 M and you add 10,00 mL of HCl (Source of H⁺) 0,1000 M. So you can see that we have the reactives of the equation (3).

We need to know what is the concentration of H⁺ for calculate the pH.

The moles of H₂PO₄⁻ are:

10,00 mL × ( 1x10⁻⁴ mol / mL) = 1x10⁻³ mol

The moles of H⁺ are, in the same way:

10,00 mL × ( 1x10⁻⁴ mol / mL) = 1x10⁻³ mol

So:

H₃PO₄   ⇄      H₂PO4⁻         +        H⁺           Kₐ₁ = 7,50x10⁻³   (3)

X mol     ⇄  (1x10⁻³-X) mol  + (1x10⁻³-X) mol                            (4)

The chemical equilibrium equation is:

Kₐ₁ = ([H₂PO4⁻] × [H⁺] / [H₃PO₄]

So:

7,50x10⁻³ = (1x10⁻³-X)² / X

Solving the equation you will obtain:

X² - 9,5x10⁻³ X + 1x10⁻⁶ = 0

Solving the quadratic formula you obtain two roots:

X = 9,393x10⁻³ ⇒ This one has no chemical logic because solving (4) you will obtain negative H₂PO4⁻ and H⁺ moles

X = 1,065x10⁻⁴

So the moles of H⁺ are : 1x10⁻³- 1,065x10⁻⁴ : 8,935x10⁻⁴ mol

The reaction volume are 20,00 mL (10,00 from both KH₂PO₄ and HCL)

Thus, the molarity of H⁺ ([H⁺]) is: 8,935x10⁻⁴ mol / 0,02000 L = 4,468x10⁻² M

pH is -log [H⁺]. So the obtained pH is 1,350

I hope it helps!

5 0
2 years ago
What does a graph representing Charles’s law show?
Juliette [100K]
<span>Volume increases at the same rate as temperature.</span>
5 0
3 years ago
Read 2 more answers
What is adaptation, and what are some examples of it?
Alja [10]
An adaption is a change or process an organism goes through to become better suited for its environment.

Example: A polar bear having white fur in order to blend in in its environment.
6 0
3 years ago
Other questions:
  • If i initially have 4.0 l of a gas at a pressure of 1.1 atm, what will the volume be if i increase the pressure of 3.4 atm?
    9·1 answer
  • Twenty irregular pieces of an unknown metal have a collective mass of 28.225 g. When carefully placed in a graduated cylinder th
    12·1 answer
  • A solution is made by dissolving 0.611 mol of NaCl in 250 g of water. If the molar mass of NaCl is 58.44 g/mol, what is the mola
    10·2 answers
  • Which race do you guys think I am (btw which picture should I post on insta?)
    7·2 answers
  • A football player with a mass of 200 kilograms sprints towards the goal line. Another football player with a mass of 120 kilogra
    9·2 answers
  • En el laboratorio, un vaso precipitado vacío tiene una masa de 0,50 kg. Este vaso se llena con 300 cm3 de una solución saturada
    10·1 answer
  • A chemical reaction occurs between Calcium, Oxygen, and Chlorine. The reaction is demonstrated:
    15·2 answers
  • Why could the amount of available freshwater decrease in an area?
    13·1 answer
  • Please help me answer Question 1.
    11·1 answer
  • Question ( please help me )
    7·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!