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Sphinxa [80]
3 years ago
15

Which of the following measurements is expressed to three significant figures?

Chemistry
2 answers:
Norma-Jean [14]3 years ago
6 0

Answer:

D

Explanation:

it goes past the decimal three places

LenKa [72]3 years ago
4 0

Answer:

C

Explanation:

A is  1 sig fig

B is 4 sig fig

C is 3 sig fig

D is 2 sig fig

Decimal places do not necessarily determine sig figs.

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Guys please I need an answer for this asap
mina [271]
I need more information, there are meant to be coefficients in front of one of those ..

but you’d put .2 over the coefficients, and if there is not one, you put an X. then you will cross multiply, and divide if you have 2x or something greater than X.
6 0
3 years ago
How many molecules of sodium oxide will be created if 275 grams of sodium reacts with excess oxygen?
DaniilM [7]

Answer:

  • <em>1.34 × 10²⁴ molecules</em>

Explanation:

To calculate the <em>number of molecules of sodium oxide that will be created if 275 grams of sodium reacts with excess oxygen</em>, use the chemical equation to calculate the number of moles and then multiply by Avogadro's number.

<u>1) Balanced chemical equation (given):</u>

  • 4Na + O₂ → 2Na₂O

<u>2) Mole ratio:</u>

  • 4 mol Na : 2 mol Na₂O

<u>3) Calculate the number of moles in 275 g  of Na:</u>

  • n = mass in grams / molar mass
  • mass of Na = 275 g
  • molar mass of Na₂O = 61.9789 g/mol

  • n = 275 g / 61.9789 g/mol = 4.437 mol of Na

<u>4) Set a proportion to find the number of moles of product (Na₂O):</u>

  • 2 mol Na₂O / 4 mol Na = x / 4.437 mol Na

  • x = 4.437 /  2 mol Na₂O = 2.2185 mol Na₂O

<u>5) Convert the number of moles to number of molecules:</u>

  • # molecules = n × 6.022 × 10²³ molecules/mol = 2.2185 mol × 6.022 × 10²³ molecules/mol = 1.34 × 10²⁴ molecules (rounded to 3 significant figures).
6 0
3 years ago
URGENT HELP NEEDED
balu736 [363]
<span>the balanced equation for the reaction is as follows
2C</span>₄H₁₀ + 13O₂ ---> 8 CO₂ + 10H₂<span>O
 stoichiometry of C</span>₄H₁₀ to O₂ <span>is 2:13
stoichiometry applies to the molar ratio of reactants and products. Avagadros law states that volume of gas is directly proportional to number of moles of gas when pressure and temperature are constant.
 Therefore volume ratio of reactants is equal to molar ratio, volume ratio of C</span>₄H₁₀ to O₂<span> is 2:13
 2 L of </span>C₄H₁₀ reacts with 13 L of O₂<span> 
then 100 L of </span>C₄H₁₀<span> reacts with 13/2 x 100 = 650 L
 therefore 650 L of O</span>₂<span> are required </span>
7 0
3 years ago
Read 2 more answers
Determine the total mass of ethanol produced when 270 g of glucose reacts completely to form ethanol and 132 g of carbon dioxide
Mekhanik [1.2K]

Answer:

138g

Explanation:

270g-132= 138g

4 0
3 years ago
Problem 3.100 a chemical plant uses electrical energy to decompose aqueous solutions of nacl to give cl2,h2, and naoh: 2nacl(aq)
chubhunter [2.5K]

First we calculate the number of moles of Cl2, that is:

moles Cl2 = 1.5*10^10 grams/71 grams/mol = 211267605.633802817 mol = 2.1 * 10 ^ 8 mole = x <span>

So that based on stoichiometry, the number of moles of NaOH = 2x and that of H2 = x mol 

mass of NaOH = 4.2*10^8 * 40 =168*10^8 grams = 1.68 * 10^6 kg = 1.68 metric tons 

<span>mass of H2 = 2.1*10^8 * 2 = 4.2*10^8 grams = 0.042 * 10^6 kg = 0.042 metric tons.</span></span>

4 0
3 years ago
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