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3 years ago

5

What it is the total length of two pieces of rubber tubing which are 7.69 cm and 4.028 cm in length? Express this answer to the

correct number of significant figures

1 answer:

Brilliant_brown [7]3 years ago

6 0

The corrects answer it 9. 45

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Balance this equation: Al+ HNO3 ---- H2 + Al(NO3)3

romanna [79]

Answer:

2Al+ 6HNO3 ---- 3H2 + 2Al(NO3)3

Explanation:

Put coefficient a,b,c, and d for calculation:

a Al + b HNO3 = c H2 + d Al(NO3)3

for Al: a = d

for H: b = 2c

for N: b = 3d

for O: 3b = 9d

Suppose a=1, then d=1, b=3, c=3/2

multiply 2 to make all natural number, a=2, then b=6, c=3, d=2

6 0

3 years ago

What does the group number of A elements in the A/B numbering system)

Ivanshal [37]

Answer:

All elements in the same A group will have the same number of

valence electrons.

Explanation:

Group A has 1 valence electrons.

4 0

4 years ago

How many sulfur dioxide<br> molecules are in 2.8 moles of<br> sulfur dioxide?<br> ?]<br> [?]x10?

marshall27 [118]

There are 1,69*10^2^4 molecules. Hope this helps. This was a hard question so if im right can u give brainliest?

8 0

3 years ago

What controls the electrical properties of the atom? the valence electron is referred to as a __________ ? when silicon atoms co

Drupady [299]

<span>It is the valence orbit that controls the electrical properties of the atom. The valence electron is referred to as a "free electron.' Valence electrons have the highest energy of all electrons in an atom; they are also the most reactive, meaning they are usually the electrons involved in bonding. When silicon atoms combine to form a solid, they arrange themselves into an orderly pattern called a crystal.</span>

7 0

3 years ago

The thermite reaction reacts iron (III) oxide, Fe2O3, with aluminium powder,Al, the form aluminium oxide, Al2O3 and iron, Fe.

lara [203]

Answer:

<u><em>This answer assumes that the strated "16.0g of iron" was meant to be 16.0 grams of iron(III) oxide.</em></u>

Explanation:

To start, the thermite equation must be balanced.

I find:

1Fe2O3 + 2Al = 1Al2O3 + 2Fe

This tells us we need 2 moles of Al for every 1 mole of Fe2O3.

Now calculate the moles of each reactant:

Moles Fe2O3: 16.0 g/159.7 g/mole = <u>0.100 moles Fe2O3</u>

Moles Al: 8.1 /26.98 g/mole = <u>0.300 moles Al</u>

The balanced equation says that in order to react all of the Fe2O3 we'd need twice that amount (in moles) of the Al. (0.100 moles Fe2O3)*(2) = 0.200 moles Al.

<u>Which of the two reactants is the limiting reagent?</u>

We have more than enough moles of Al to react with 0.10 moles of Fe2O3. (We have 0.300 moles Al and all we need is 0.200 moles to react with the 0.10 moles of Fe2O3. <em>Fe2O3 is the limiting reagent.</em>

<u><em>Calculate the maximum mass of iron of iron that could be formed using these quantities of reactants.</em></u>

The balanced equation tells us that we will obtain 2 moles of Fe for every 1 mole of Fe2O3 consumed. Since Fe2O3 is the limiting reagent, we will assume that it completely reacts. That means 0.1 moles of Fe2O3 is reacted. Since we expect twice that many moles of Fe, we should obtain 0.200 moles of Fe. At 55.85 g/mole, we should obtain:

(0.200 moles Fe)*(55.85 g Fe/mole Fe) = 11.2 grams Fe

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5 0

2 years ago