Which scientist observed that compounds are always joined together in fixed ratios?

OverLord2011 [107]

A scale factor is it

5 0

3 years ago

Convert the composition of the following alloy from atom percent to weight percent (a) 44.9 at% of silver, (b) 46.3 at% of gold,

vesna_86 [32]

Answer:

Mass percentage of gold : 33.35%

Mass percentage of silver: 62.80%

Mass percentage of copper : 3.85%

Explanation:

$N=n\times N_A$

Where : N = Number of atoms

n = moles

$N_A=6.022\times 10^{23}$ = Avogadro number

Let the total atoms present in the alloy be 100.

Atom percentage of silver = 44.9%

Atoms of of silver = 44.9% of 100 atoms = 44.9

Atomic weight of silver = 107.87 g/mol

Mass of 44.9 silver atoms = 107.87 g/mol × 44.9 = 4,843.363 g/mol

Atom percentage of gold= 46.3%

Atoms of of gold = 46.3% of 100 atoms = 46.3

Atomic weight of gold = 196.97 g/mol

Mass of 44.9 gold atoms = 196.97 g/mol × 46.3 = 9,119.711 g/mol

Atom percentage of copper = 8.8 %

Atoms of of copper = 8.8% of 100 atoms = 8.8

Atomic weight of copper = 63.55 g/mol

Mass of 44.9 copper atoms = 63.55 g/mol × 8.8 = 559.24 g/mol

Total mass of an alloy :4,843.363 g/mol + 9,119.711 g/mol + 559.24 g/mol

Mass percentage of gold :

$\frac{4,843.363 g/mol}{4,843.363 g/mol + 9,119.711 g/mol + 559.24 g/mol}\times 100=33.35 \%$

Mass percentage of silver:

$\frac{9,119.711 g/mol}{4,843.363 g/mol + 9,119.711 g/mol + 559.24 g/mol}\times 100=62.80\%$

Mass percentage of copper :

$\frac{559.24 g/mol}{4,843.363 g/mol + 9,119.711 g/mol + 559.24 g/mol}\times 100=3.85\%$

7 0

3 years ago

Both kepler's laws and newton's laws tell us something about the motion of the planets, but there are fundamental differences be

I am Lyosha [343]

Answer: See description

Explanation:

Kepler's laws have three principal points:

1. planets orbit the sun in elliptical paths

2. the orbial period is related to the orbital distance by $T^{2} = d^3$

where T is the orbital period and d is the orbital distance, T is in years and d is measured in units of the earth sun distance.

3. planets closer to the sun move faster than planets far away from it.

Newton:

Newton discovered that there is a consequence to the gravity exerted by objects: mass, the heavier the planet, the more gravitational force it posseses ( thats why we orbit the sun)

with the gravitational force $F_{gravitational} =G \frac{Mm}{r^2}$ newton discovered the inverse-quadratic relationship between the distance of the planets and the acceleration exerted by the force one could exert on another.

Kepler's laws were mostly based on observed evidence with quantitative relationships between the mentioned variables. Newton's laws are based on calculus and symbolic equations. While Kepler's mode is basic, Newton took another step in and build a more general model for gravity (which was improved by general relativity later). In a nutshell Newton proved the scientific causes for Kepler's laws...

3 0

3 years ago

If 185 mg of acetaminophen were obtained from a tablet containing 350 mg of acetamino- phen, what would be the weight percentage

Alex73 [517]

Percentage recovery gives us an idea of the amount of pure substance recovered after the chemical reaction. Percentage recovery can be more than 100 % or less than 100 %. Usually, in any experiment performed the weight percentage recovery will be less than 100. Percent recovery values greater than 100 show that the recovered compound is contaminated.

Amount of acetaminophen initially taken = 350 mg

Amount of acetaminophen obtained after recovery =185 mg

$Weight percentage recovery =\frac{mass recovered}{mass originally taken}*100$

= $\frac{185 mg}{350 mg}*100$

= 52.9%

8 0

3 years ago

Why is salt a mineral

shutvik [7]

Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. ... Salt is essential for life in general, and saltiness is one of the basic human tastes

8 0

2 years ago

Read 2 more answers