The radius of a circle is 7.31. How should the circle area be reported?

Chemistry

1 answer:

Alona [7]3 years ago

7 0

I'm not sure but it should be 7.31 times 2 times 3.14 or pi

7.31 x 2 x 3.14 = 45.9068

If you need to round to the nearest tenth it will be 45.9

If you need to round to the nearest hundredth it will be 45.91

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A 150 mL of oxygen gas is collected over water at 20 °C and 758 torr. What volume will the same sample of oxygen occupy at STP w

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Answer:

The volume would be; 136.17 ml

Explanation:

Volume V1 = 150 mL

Temperature T1 = 20°C + 273 = 293 K

Pressure P1 = 758 - 17.54 = 740.46 torr

At STP;

Volume V2 = ?

Pressure P2 = 760 torr

Temperature T2 = 273 K

Using the general gas equation;

P1V1 / T1 = P2V2 / T2

Making V2 subject of formulae;

V2 = P1V1T2 / T1P2

Inserting the values we have;

V2 = 740.46 * 150 * 273 / 293 * 760

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How many liters of hydrogen gas is produced from 3.712 g of magnesium with 104.2ml of 1.385 mol/L HCL (aq) at SATP? Please show

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Answer:

$V=1.61L$

Explanation:

Hello,

In this case, the undergoing chemical reaction is:

$Mg+2HCl\rightarrow MgCl_2+H_2$

Next, we compute the reacting moles of each reactants:

$n_{Mg}=3.712gMg*\frac{1molMg}{24.305 gMg}=0.153molMg$

$n_{HCl}=1.385\frac{molHCl}{L}*0.1042L=0.144molHCl$

Then, as magnesium and hydrohloric acid are in a 1:2 molar ratio 0.153 moles of magnesium will completely react with 0.306 moles of hydrochloric acid yet we only have 0.144 moles, therefore, limiting reactant is hydrochloric acid. Thus, we compute the produced moles of hydrogen:

$n_{H_2}=0.144molHCl*\frac{1molH_2}{2molHCl} =0.072molH_2$