Balance the following reaction _ Al + _ Cl, →

When would you want to be at the beach during a spring tide?

meriva

I would want to be at the beach during the spring.

8 0

3 years ago

Calculate the number of O atoms in 0.364 g of CaSO4 · 2H2O

Nikolay [14]

Answer:

= 7.66 x 10²¹ oxygen atoms in 0.364 grams of CaSO₄·2H₂O

Explanation:

For problems like this posting, one needs an understanding of the following topics:

The definition of the mole

1 mole of substance = mass in grams of substance containing 1 Avogadro's Number ( = 6.023 x 10²³ ) of particles of the specified substance. This is generally one formula weight of the substance of interest. From this, the following equivalent relationships should be memorized:

1 mole = 1 formula weight = 1 mole weight (g)= 6.023 x 10²³ particles

Converting grams to moles:

Given grams => moles = grams/gram formula wt

Converting moles to grams:

Given moles => grams = moles x gram formula wt

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Calculate the number of O atoms in 0.364 g of CaSO₄ · 2H₂O.

Given mass CaSO₄ · 2H₂O = 0.364 grams

Formula Wt CaSO₄ · 2H₂O = 172 g/mole

moles CaSO₄ · 2H₂O = mass CaSO4 · 2H2O / formula Wt. CaSO₄ · 2H₂O

= 0.364 g CaSO₄·2H₂O / 172 g CaSO4·2H2O

= (0.364/172) mole CaSO₄·2H₂O

= 2.12 x 10⁻³ mole CaSO₄·2H₂O

∴ number of Oxy (O) atoms in 0.364 grams CaSO₄·2H₂O

= (2.12 x 10⁻³ mole CaSO₄ · 2H₂O)(6.023 x 10²³ molecules CaSO₄· 2H₂O/ mole)

= 1.276876 x 10²¹molecules CaSO₄· 2H₂O CaSO₄2H₂O

= 1.276876 x 10²¹ molecules CaSO₄· 2H₂O x 6 oxygen atoms / molecule

= 7.661256 x 10²¹ oxygen atoms in 0.364 grams of CaSO₄·2H₂O

= 7.66 x 10²¹ oxygen atoms in 0.364 grams of CaSO₄·2H₂O

8 0

2 years ago

What is the pH of a solution whose H + concentration is 4.0 10 –9?

Dmitrij [34]

Answer:

he pH of a solution is defined as the negative log10 [H+] ... 1 x 10-11. 11. Acidic Solution. 1 x 10-4. 4. 1 x 10-10. 10. 1 x 10-5. 5. 1 x 10-9.

Explanation:

m

5 0

2 years ago

Lithium-4 and Lithium-5 can be defined as:

Ludmilka [50]

Answer:

A: isotopes

Explanation:

Hello.

In this case, since isotopes are defined as atoms of the same element with the same atomic number (number of protons and electrons) but different mass number (atomic mass) we can represent them via the symbol of the element followed by a dash indicating the atomic mass of the occurring isotope, for instance, for carbon, we may find C-12, C-13 and even C-14 which is useful in dating techniques.

Therefore, Lithium-4 or Li-4 and Lithium-5 or Li-5 can be defined as isotopes.

Best regards.

8 0

3 years ago

Read the descriptions below of two substances and an experiment on each. Decide whether the result of the experiment tells you t

muminat

Answer:

Sample A is a pure substance

Sample B is a mixture

Explanation:

We are told that the when the yellow solid, sample A is ground it turned to orange colour and was then dissolved. Some part of the solid settled out at the bottom of the beaker while some part floated on top of the water. 50g of the solid was dissolved and 50.1g of the solid was recovered.

This implies that the substance is pure since the mass dissolved was almost the same mass recovered. The 0.1g addition in mass may result from incomplete drying of the solid.

For sample B, the distillation of the sample of density 0.77 g/ml left a fraction in the beaker with density 1.04 g/ml indicating that the substance is a mixture. Different components of a mixture possess different densities.

5 0

2 years ago

Balance the following reaction _ Al + _ Cl, → _ AICI,