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4 years ago

The order of elements in the periodic table is based on of elements in the periodic table is based on

Chemistry

2 answers:

Serhud [2]4 years ago

6 0

The increasing atomic number

gizmo_the_mogwai [7]4 years ago

3 0

It is based on the atomic number

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Which of the following is the correct scientific notation for 0.0000782 g?

Dominik [7]

The correct scientific notation is 7.82 x 105 g

7 0

3 years ago

Read 2 more answers

If you react 2.00 g of hydrogen completely using 15.87 g of oxygen to produce water, how much water (in grams) will you have?

leonid [27]

Answer:

The amount (mass) of water we will have is 17.869 grams

Explanation:

The molar mass of hydrogen gas H₂ = 2.016 grams/mole

The molar mass of oxygen gas = 31.999 g/mol

Therefore, 2.00 g of hydrogen will give;

2.00/2.016 = 0.9921 moles of H₂ gas and

15.87 g of O₂ will give;

15.87/31.999 = 0.49595 moles

The reaction is as follows;

2H₂ (g) + O₂ (g) → 2H₂O (l)

Two moles of H₂ react with one mole of O₂ to produce two moles of H₂O

Therefore 0.9921 moles of H₂ will react with 0.9921/2 or 0.49595 moles of O₂ to produce 0.9921 moles of H₂O

From the above we note that all the H₂ and O₂ are completely consumed to form 0.9921 moles of H₂O

Molar mass of H₂O = 18.01528 g/mol

Number of moles = Mass/(Molar mass)

∴ Mass of H₂O = (Molar mass) × (Number of moles)

= 18.01528 g/mol × 0.9921 moles = 17.869 grams

Therefore the amount (mass) of water we will have = 17.869 grams.

8 0

3 years ago

Another simple question and I need it bad

podryga [215]

Oh this is extremely hard...i might just die lol jk its the last one measuring cylinder :)

3 0

3 years ago

Read 2 more answers

The half-life of tritium, or hydrogen-3, is 12.32 years. After about 24.6 years, how much of a sample of tritium will remain unc

scoundrel [369]

Answer: The correct option is B.

Explanation: This is an example of radioactive decay and all the radioactive decay processes follow First order of kinetics.

Expression for the half life of first order kinetics is:

$t_{1/2}=\frac{0.693}{k}$

We are given:

$t_{1/2}=12.32years$

Putting in above equation, we get:

$12.32=\frac{0.693}{k}\\k=0.05625year^{-1}$

Expression to calculate the amount of sample which is unchanged is:

$N=N_oe^{-kt}$

where,

N = Amount left after time t

$N_o$ = Initial amount

k = Rate constant

t = time period

Putting value of k = 0.05625 and t = 24.6 in above equation, we get:

$N=N_oe^{-0.05625\times 24.6}$

$\frac{N}{N_o}=0.25$

The above fraction is the amount of sample unchanged and that is equal to $\frac{1}{4}$

Hence, the correct option is B.

8 0

3 years ago

Read 2 more answers

How many moles of aluminum are needed to make 9 moles of molecular hydrogen? Given the reaction: 2 Al + 6 HCl → 2 AlCl3 + 3H2

VMariaS [17]

Answer:

We need 6.0 moles of aluminium

Explanation:

Step 1: Data given

Number of moles of H2 = 9.0 moles

Step 2: The balanced equation

2 Al + 6 HCl → 2 AlCl3 + 3H2

Step 3: Calculate moles Al

For 2 moles Aluminium, we need 6 moles HCl to produce 2 moles AlCl3 and 3 moles H2

For 9.0 moles of H2 we need 2/3 * 9.0 = 6.0 moles of aluminium

We need 6.0 moles of aluminium

6 0

3 years ago