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3 years ago

The United States rallied to the aid of Cuba in 1898 mainly because it

Chemistry

2 answers:

Mkey [24]3 years ago

6 0

The answer is C Had a military base to protect

MissTica3 years ago

5 0

C. had a military base to protect

it was established in 1820 and was just getting trainees and recruits when this happened

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Which feature is created on the exterior of a volcano when it erupts?

Flura [38]

Answer:

When the magma reaches it boiling point and it starts to rise

Explanation:

3 0

3 years ago

Jimmy developed a model to show the difference between pure substances and mixtures

IrinaK [193]

Pure substances cannot be separated into any other kinds of matter, while a mixture is a combination of two or more pure substances.
A pure substance has constant physical and chemical properties, while mixtures have varying physical and chemical properties.

<u>Explanation:</u>

A matter which cannot be separated into any other kind of matter using the chemical or physical process is called pure substances. A pure substance has the same color, composition, and texture.
An element consisting of a single compound with a definite composition, physical and chemical properties are called pure substances.
A combination that has as of many substances that are not united using a chemical procedure or any process is known as mixtures. A mixture does not exist in fixed proportions, and most of the natural substances are mixtures.

8 0

3 years ago

If your heart beats an average of 68 times per minute, how many times will your heart beat in an hour? In a day? In a week? Show

Georgia [21]

Per hour-68x60=4080
Per day-4080x24=97920
Per week-97920x7=685440

3 0

3 years ago

a mixture is made up of 3.35g of SiO2, 0.38g of cellulose and 8.76g of calcium carbonate. What is the percent of cellulose in th

Alchen [17]

Solution:

mass of the cellulose in the mixture is 0.38g

total mass of the mixture is:

3.35+0.38+8.76

=12.4g

thus the percentage of the cellulose in the mixture is:

mass of the cellulose/total mass of the mixture*100%

0.38/12.4*100%

=3%

6 0

3 years ago

A natural water with a flow of 3800 m3/d is to be treated with an alum dose of 60 mg/L. Determine the chemical feed rate for the

svet-max [94.6K]

Explanation:

First, we will calculate the feed rate of alum as follows.

$\frac{\text{60 mg alum}}{\text{1 L water}} \times \frac{\text{1000 L water}}{1 m^{3}} \times \frac{3800 m^{3}}{day} \times \frac{\text{1 g alum}}{\text{1000 mg alum}}$

= 228000 g/day

Converting this amount into g/min as follows.

$\frac{228000 g}{1 day} \times \frac{1 day}{1440 min}$

= 158 g/min

Now, the chemical equation will be as follows.

$Al_{2}(SO_{4})_{3}.14H_{2}O \rightarrow 2Al(OH)_{3}(s) + 6H^{+} + 3SO^{2-}_{4} + 8H_{2}O$

$\frac{\text{30 mg alum}}{1 L} \times \frac{\text{1 mmol alum}}{\text{594 mg alum}} \times \frac{\text{3 mmol SO^{2-}_{4}}}{\text{1 mmol alum}}$

= 0.151 mmol $mmol SO^{2-}_{4}/L$

$\frac{0.151 mmol SO^{2-}_{4}}{L} \times \frac{\text{2 meq SO^{2-}_{4}}}{\text{1 mmol SO^{2-}_{4}}} \times \frac{\text{1 meq Alk}}{\text{1 meq SO^{2-}_{4}}} \times \frac{\text{50 mg CaCO_{3}}}{\text{1 meq Alk}}$

= 15.15 mg $CaCO_{3}$ /L

For precipitate:

$Al_{2}(SO_{4})_{3}.14H_{2}O \rightarrow 2Al(OH)_{3}(s) + 6H^{+} + 3SO^{2-}_{4} + 8H_{2}O$

$\frac{\text{30 mg alum}}{1 L} \times \frac{\text{1 mmol alum}}{\text{594 mg alum}} \times \frac{\text{2 mmol Al(OH)_{3}}}{\text{1 mmol alum}} \times \frac{\text{78 mg Al(OH)_{3}}}{\text{1 mmol Al(OH)_{3}}}$

= 7.88 $Al(OH)_{3}/L$

$\frac{7.88 mg Al(OH)_{3}}{1 L} \times \frac{3800 m^{3}}{1 day} \times \frac{1000 L}{1 m^{3}} \times \frac{1 kg}{10^{6} mg}$

= 29.9 $Al(OH)_{3}/day$

3 0

4 years ago