When the equation __H2O2 --> __H2O + __O2 Is completely balanced, the sum of all the coefficients will be A) 5 B) 8 C) 3 D) 4

A party balloon contains 5.50 x 10 ^22 atoms of helium gas. What is the mass, in grams of the

eduard

Answer:

$\boxed {\boxed {\sf A. \ 0.365 \ g\ He}}$

Explanation:

1. Convert Atoms to Moles

We must use Avogadro's Number: 6.022*10²³. This is the number of particles (atoms, molecules, ions, etc.) in 1 mole of a substance. In this case, the particles are atoms of helium. We can create a ratio.

$\frac {6.022*10^{23} \ atoms \ He}{1 \ mol \ He}$

Multiply by the given number of helium atoms.

$5.50 *10^{22} \ atoms \ He *\frac {6.022*10^{23} \ atoms \ He}{1 \ mol \ He}$

Flip the fraction so the atoms of helium cancel.

$5.50 *10^{22} \ atoms \ He *\frac {1 \ mol \ He}{6.022*10^{23} \ atoms \ He}$

$5.50 *10^{22} *\frac {1 \ mol \ He}{6.022*10^{23} }$

$\frac {5.50 *10^{22} \ mol \ He}{6.022*10^{23} }= 0.09133178346 \ mol \ He$

2. Convert Moles to Grams

We must use the molar mass, which is found on the Periodic Table.

Helium (He): 4.00 g/mol

Use this as a ratio.

$\frac { 4.00 \ g \ He }{ 1 \ mol \ He}$

Multiply by the number of moles we calculated. The moles will then cancel.

$0.09133178346 \ mol \ He *\frac { 4.00 \ g \ He }{ 1 \ mol \ He}$

$0.09133178346*\frac { 4.00 \ g \ He }{ 1 }$

$0.3653271338 \ g\ He$

3. Round

The original measurement has 3 significant figures (5, 5, and 0). Our answer must have the same. For the number we calculated, it is thousandth place. The 3 in the ten thousandth place tells us to leave the 5.

$0.365 \ g\ He$

The mass is 0.365 grams of helium so choice A is correct.

7 0

2 years ago

For a representative element, the row number on the periodic chart will be the same as the shell number. TRUE OR FALSE

OLEGan [10]

True. Row number on the periodic chart will be the same as the shell number.

8 0

2 years ago

Explain how the structure and bonding in bromine account for it's relatively low melting point. [3]

Sever21 [200]

Melting point is dependent on the intermolecular forces which means the bonds between the molecules of bromine as it is a simple molecular structure the intermolecular bonds of bromine are weak bcz they are weak vandervaal forces thats why Bromines melting point is low..In short when intermolecular bomds are weak the M.P is lower

6 0

2 years ago

Read 2 more answers

What characteristic frequencies in the infrared spectrum of your sodium borohydride reduction product will you look for to deter

kkurt [141]

Answer:

A)The characteristic frequency to look out for is 1720-1740 cm-1 (for C=O) for which will disappear in the end product but initially present in the reactant.

B)Characteristic frequency present in the infrared spectrum will be at a peak of 3300-3400 cm-1 which will be due to O-H stretch.

C)If the product is wet with water there will be no change in the infrared spectrum

Explanation:

The characteristic frequency to look out for is 1720-1740 cm-1 (for C=O) for which will disappear in the end product but initially present in the reactant.

Characteristic frequency present in the infrared spectrum will be at a peak of 3300-3400 cm-1 which will be due to O-H stretch.

If the product is wet with water there will be no change in the infrared spectrum

5 0

2 years ago

Help me clarify please!

zaharov [31]

Answer:

Round to the number of significant figures in the original question. However, if you're going to proceed with further calculations using this mass, it's best not to round, as rounding will cause your answer to be less precise.

Explanation:

7 0

1 year ago