Answer:
Oxygen's mass percent in Fe(OH)3 is 44.92%
Explanation: The mass percentage is a means of indicating the concentration of a specific element within a compound. It is determined through the ratio of the element's mass to the compound's total mass, multiplied by 100.
•First calculate the overall mass of the compound
•Fe's molar mass = 55.85 g/mol
•O's molar mass = 16 g/mol
•H's molar mass = 1 g/mol
Using these values, we can compute the molecular mass of Fe(OH)3 = 55.85 g/mol + (16 g/mol)3 + (1 g/mol)3
=55.85 g/mol + 48 g/mol + 3 g/mol
=106.85 g/mol
Mass percent of an element = mass of element/total mass of compound × 100
In the case of 3 oxygen atoms present within the compound, the mass of oxygen totals 48 g/mol
Mass percent of oxygen= 48 g/mol/106.85 g/mol × 100
= 0.4492×100= 44.92%
[[TAG_31]]Thus, the mass percent of oxygen in Fe(OH)3 amounts to 44.92%[[TAG_32]]
Response:
9.606 g
Clarification:
Step 1: Write the balanced combustion equation
C₂H₆O(l) + 3 O₂(g) → 2 CO₂(g) + 3 H₂O(g)
Step 2: Determine the moles for 11.27 g of H₂O
The molar mass of H₂O is 18.02 g/mol.
11.27 g × (1 mol/18.02 g) = 0.6254 mol
Step 3: Find the moles of C₂H₆O that produced 0.6254 moles of H₂O
The ratio of C₂H₆O to H₂O is 1:3. Thus, the moles of C₂H₆O are 1/3 × 0.6254 mol = 0.2085 mol
Step 4: Calculate the mass for 0.2085 moles of C₂H₆O
The molar mass of C₂H₆O is 46.07 g/mol.
0.2085 mol × 46.07 g/mol = 9.606 g
A. 1.01 is the accurate result
Because
The formula used is Pv= nRT
P=1 atm
V= 22.4 L
N= x
R= 0.0821
T= 273 K (since it’s standard temperature)
Thus, (1)(22.4)=(x)(0.0821)(273)
X= 1.001
Your Question: There are two kinds of elements that didn't appear on the periodic table until after 1892. What kinds are they and why do you think it took so long to discover them?
The Answer: The insights of Moseley led chemists to further refine the periodic table and uncover additional gaps, indicating that several new elements, specifically with atomic numbers 43, 61, 72, and 75, remained undiscovered. These elements were later identified as technetium, promethium, hafnium, and rhenium, respectively.
Explanation: Physicist Henry Moseley used x-rays to determine the atomic number of elements, which facilitated a more accurate organization of the periodic table. His life and the discovery of the correlation between atomic number and x-ray frequency, known as Moseley's Law, are significant to note.
Remember to consult study guides, lessons, and notes; hard work is essential for success. Good Luck!
Yasir wished to explore how sleep relates to room color. He conducted necessary preliminary research and formed a hypothesis suggesting individuals doze off faster in blue-painted rooms compared to those painted in yellow. Yasir surveyed several individuals about their color preference—yellow or blue—and utilized their feedback to assess the validity of his hypothesis. However, he did not conduct an actual experiment to examine the impact of room color on sleep, and he failed to clearly define the variables that should have been part of his experiment.
Hence, the correct answer would be,
An experiment that directly tests the hypothesis
Variables to be tested by an experiment
