A chemical change occurs when substances chemically react with one another. true or false

Calculate the atomic mass of lead. The four lead isotopes have atomic masses and relative abundances of 203.973 amu (1.4%), 205.

blondinia [14]

207.217 amu
Work:
203.973 amu *(0.014) = 2.855 amu
205.974 amu *(0.241) = 49.639 amu
206.976 amu *(0.221) = 45.741 amu
207.977 amu *(0.524) = 108.979 amu

2.855 + 49.639 + 45.741 + 108.979 = 207.217 amu

8 0

3 years ago

Using the development of the atomic model.explain how scientists refine and build off each other’s findings, in order to develop

sineoko [7]

<span>The Atomic Model was something that was first developed by Neils Bohr. Several years later, Schrodinger took Bohr's basis of a theory and developed it into something larger. So as we can see, theories are a bit like puzzles. When first starting out, one person develops something, or has an idea on something. Others trying to either prove or disprove the original findings, will then test things in a new way, revealing more and more of the puzzle. As the puzzle becomes more and more clear, there is more and more that is revealed. Eventually, we get to a point where we have almost the entire picture, however we are still missing a few key pieces that complete the puzzle. We can see the big picture, but you can not exactly prove out what exactly the details are. This is how scientists such as Bohr and Schrodinger use each others research to build and refine theories. Eventually, we reach a point where we are only missing maybe one or two pieces, and at that point, a theory transitions into almost fact, such as evolution.</span>

7 0

3 years ago

A cylinder contains 4.0 g of nitrogen gas. A piston compresses the gas to half its initial volume. Afterward, by what factor has

notka56 [123]

Answer:

The mass density will be doubled

Explanation:

Density is given by dividing the mass of a substance by its volume.
An increase in mass causes an increase in density and vice versa, while a decrease in volume causes an increase in density and volume.
Therefore, when the volume is halved, then the density will be doubled if the mass is kept constant.
This has no effect on the number of moles as the mass is constant.

8 0

3 years ago

How waves affect matter at the macroscopic and particle levels?

solmaris [256]

Reflection, refraction, and diffraction

Reflection occurs when waves bounce back from a surface that they cannot pass through. Refraction occurs when waves bend as they enter a new medium at an angle and start traveling at a different speed.

5 0

3 years ago

Use the following table to answer the question. Strong acids Weak acids Weak bases Strong bases HBr CH3COOH NH3 NaOH HCl HF NH4O

Y_Kistochka [10]

Answer: The salt which has the highest pH is $CH_3COONa$

Explanation: Salts are formed by the reaction of acid and base. General equation for the generation of salt is given by:

$HX+BOH\rightarrow BX+H_2O$

The given salts are formed from the reaction of acids and bases.

1) $K_2SO_4$

This is a salt formed by the reaction of strong base (KOH) and strong acid $(H_2SO_4)$ . So, this salt is a neutral salt.

$H_2SO_4+2KOH\rightarrow K_2SO_4+2H_2O$

2) $CuSO_4$

This is a salt which is formed by the reaction of weak base $(Cu(OH)_2)$ and strong acid $(H_2SO_4)$ . So, this salt is an acidic salt.

$H_2SO_4+Cu(OH)_2\rightarrow CuSO_4+2H_2O$

3) $NH_4Cl$

This is a salt which is formed by the reaction of weak base $(NH_3)$ and strong acid (HCl). So, this salt is an acidic salt.

$HCl+NH_3\rightarrow NH_4Cl$

4) $CH_3COONa$

This is a salt which is formed by the reaction of strong base (NaOH) and weak acid $(CH_3COOH)$ . So, this salt is a basic salt.

$CH_3COOH+NaOH\rightarrow CH_3COONa+H_2O$

Now, we have to find the salt which has the highest pH value.

Highest pH value means that the salt must be basic in nature and from the given salts, only $CH_3COONa$ is basic salt. Hence, this salt has the highest pH value.

6 0

3 years ago

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