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juin [17]
3 years ago
12

What is the atomic mass of Si in units of amu?

Chemistry
1 answer:
tekilochka [14]3 years ago
8 0
The amu would be 28.0855
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If 25.0 ml of seawater has a mass of 25.895 g and contains 1.295 g of solute, what is the mass/mass percent concentration of sol
Romashka-Z-Leto [24]
The  %  mass/mass concentration  of   solute  in the  seawater  sample  is  calculated  as  below


% mass =  mass  of the  solute /mass of the solvent(sea water)  x100
mass  of  the  solute =1.295  g
mass  of the  solvent(sea   water_)  =  25.895 g

there  the % mass =  1.295/25.895  x100 =  5.001 %  
8 0
3 years ago
Need help !!!!! ASAP
Nat2105 [25]
<h2>Hello!</h2>

The answer is:

The temperature will be the same, 37°C.

<h2>Why?</h2>

Since from the statemet we know the first temperature, pressure and volumen of a gas, and we need to calculate the new temperature after the pressure and the volume changed, we need to use the Combined Gas Law.

The Combined Gas Law establishes a relationship between the temperature, the pressure and the volume of an ideal gas using Boyle's Law, Gay-Lussac's Law and Charles's Law.

The law establishes the following equation:

\frac{P_{1}V{1}}{T_{1}}=\frac{P_{2}V{2}}{T_{2}}

Where,

P_{1} is the first pressure.

V_{1} is the first volume.

T_{1} is the first temperature.

P_{2} is the second pressure.

V_{2} is the second volume.

T_{2} is the second temperature.

Then, we are given the following information:

V_{1}=200mL\\P_{1}=4atm\\T_{1}=37\°C\\V_{2}=400mL\\P_{2}=2atm

So, isolating the new temperature and substituting the given information, we have:

\frac{P_{1}V{1}}{T_{1}}=\frac{P_{2}V{2}}{T_{2}}\\\\T_{2}=P_{2}V{2}*\frac{T_{1}}{P_{1}V_{1}} \\\\T_{2}=2atm*400mL*\frac{37\°C}{4atm*200mL}=37\°C

Hence, we have that the temperature will not change because both pressure and volume decreased and increased proportionally, creating the same relationship that we had before the experiment started.

The temperature will be the same, 37°C

Have a nice day!

4 0
3 years ago
What is true about asteroids
Igoryamba

Answer:

They are big rocks that fly through space and are made of most commonly chondrite. When they collide, they collide with such force that they create craters on places like the moon.

7 0
2 years ago
Astatine is a halogen with several isotopes that all have short half-lives. Which of the following combinations of mass number a
DedPeter [7]

Answer:

Astatine is a halogen with several isotopes that all have short half-lives.

Which of the following combinations of mass number and neutrons are possible as isotopes of astatine? Choose one or more:

i) A = 211, n = 127

ii) A = 210, n = 125

iii) A = 220, n = 134

iv) A = 207, n = 122

v) A = 209, n = 124

Explanation:

The mass number is the sum of the number of protons and the number of neutrons in an atom.A=no.of protons+no.of neutrons\\=>no.of neutrons=A-no.of protons\\

Atomic number of At(astatine ) =85

That means it has --- 85protons.

Its mass number A=210

Hence, the number of neutrons in At are:

n=A-Z\\=>n=210-85\\=>n=125

Second option:

ii) A=210 , n=125 is the answer.

4 0
3 years ago
A solution prepared by dissolving 0.100 mole of propionic acid in enough water to make 1.00 L of solution is observed to have a
torisob [31]

Answer:

C) k_a=1.3\times 10^{-5}

Explanation:

pH is defined as the negative logarithm of the concentration of hydrogen ions.

Thus,  

pH = - log [H⁺]

The expression of the pH of the calculation of weak acid is:-

pH=-log(\sqrt{k_a\times C})

Where, C is the concentration = 0.5 M

Given, pH = 2.94

Moles = 0.100 moles

Volume = 1.00 L

So, Molarity=\frac{Moles}{Volume}=\frac{0.100}{1.00}\ M=0.100\ M

C = 0.100 M

2.94=-log(\sqrt{k_a\times 0.100})

\log _{10}\left(\sqrt{k_a0.1}\right)=-2.94

\sqrt{0.1}\sqrt{k_a}=\frac{1}{10^{2.94}}

k_a=1.3\times 10^{-5}

4 0
3 years ago
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