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3 years ago

Which of the following could be a unit in the customary system?

Chemistry

2 answers:

Dmitry [639]3 years ago

5 0

The answer is Foot I believe

STatiana [176]3 years ago

4 0

Kilometer is the answer to this question..

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A reaction of 41.9 g of Na and 30.3 g of Br2 yields 36.4 g of NaBr . What is the percent yield?

Licemer1 [7]

Answer: The percent yield is, 93.4%

Explanation:

First we have to calculate the moles of Na.

$\text{Moles of Na}=\frac{\text{Mass of Na}}{\text{Molar mass of Na}}=\frac{41.9g}{23g/mole}=1.82moles$

Now we have to calculate the moles of $Br_2$

${\text{Moles of}Br_2} = \frac{\text{Mass of }Br_2 }{\text{Molar mass of} Br_2} =\frac{30.3g}{160g/mole}=0.189moles$

${\text{Moles of } NaBr} = \frac{\text{Mass of } NaBr }{\text{Molar mass of } NaBr} =\frac{36.4g}{103g/mole}=0.353moles$

The balanced chemical reaction is,

$2Na(s)+Br_2(g)\rightarrow 2NaBr$

As, 1 mole of bromine react with = 2 moles of Sodium

So, 0.189 moles of bromine react with = $\frac{2}{1}\times 0.189=0.378$ moles of Sodium

Thus bromine is the limiting reagent as it limits the formation of product and Na is the excess reagent.

As, 1 mole of bromine give = 2 moles of Sodium bromide

So, 0.189 moles of bromine give = $\frac{2}{1}\times 0.189=0.378$ moles of Sodium bromide

Now we have to calculate the percent yield of reaction

$\%\text{ yield}=\frac{\text{Actual yield}}{\text{Theoretical yield}}\times 100=\frac{0.353 mol}{0.378}\times 100=93.4\%$

Therefore, the percent yield is, 93.4%

3 0

3 years ago

In the activity, click on the E∘cell and Keq quantities to observe how they are related. Use this relation to calculate Keq for

inessss [21]

Answer:

The standard cell potential of the reaction is 0.78 Volts.

Explanation:

$Cu^{2+}(aq)+Fe(s)\rightarrow Cu(s)+Fe^{2+}(aq)$

Reduction at cathode :

$Cu^+(aq)+2e^-\rightarrow Cu(s)$

Reduction potential of $Cu^{2+}$ to Cu= $E^o_{1}=0.34 V$

Oxidation at anode:

$Fe(s)\rightarrow Fe^{2+}(aq)+2e^-$

Reduction potential of $Fe^{2+}$ to Fe= $E^o_{2}=-0.44 V$

To calculate the $E^o_{cell}$ of the reaction, we use the equation:

$E^o_{cell}=E^o_{red,cathode}-E^o_{red,anode}$

Putting values in above equation, we get:

$E^o_{cell}=0.34V -(-0.44 V)=0.78 V$

The standard cell potential of the reaction is 0.78 Volts.

3 0

3 years ago

When a radioactive isotope releases an alpha particle, the atomic number of the atom is (2 points)

natali 33 [55]

When alpha decay takes place, two protons and two neutrons are forcefully ejected from the nucleus in a way that looks very similar to a Helium nucleus. This type of decay causes the atomic mass of the parent particle to drop by four (four particles lost), but the atomic number drops by only two (two protons lost). Therefore, your answer is C.

8 0

3 years ago

Read 2 more answers

30 Pointss<br> Please make sure it is correct please

Vsevolod [243]

Answer:

Option C is correct.

Explanation:

The graph shows birth and death rate in Japan. Birth rate has declined with the passage of time, as shown in the form of blue line whereas death rate is nearly constant, which can be seen as red line. More precisely, birth rate has decreased from ~30 to 10 whereas death rate is nearly ~10 all the times, although it was slightly decreased in the middle. Therefore, option C is the correct option...

6 0

3 years ago

PLease help my imma mark brainlist plsss

iogann1982 [59]

Answer:

Chemical reactions that absorb (or use) energy overall are called endothermic. In endothermic reactions, more energy is absorbed when the bonds in the reactants are broken than is released when new bonds are formed in the products.

4 0

2 years ago