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2 years ago

NEED HELP ASAP!!!! 7th grade Science!!!

Chemistry

2 answers:

Mazyrski [523]2 years ago

6 0

Answer:C2H4

Explanation:

O=Oxygen, there is no oxygen

masha68 [24]2 years ago

5 0

Answer:

C2H4

Explanation:

This compound has no oxygen atoms at all.

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When 6.040 grams of a hydrocarbon, CxHy, were burned in a combustion analysis apparatus, 18.95 grams of CO2 and 7.759 grams of H

algol [13]

Answer: The empirical formula is $CH_2$ and molecular formula is $C_4H_8$

Explanation:

We are given:

Mass of $CO_2$ = 18.95 g

Mass of $H_2O$ = 7.759 g

Molar mass of carbon dioxide = 44 g/mol

Molar mass of water = 18 g/mol

For calculating the mass of carbon:

In 44g of carbon dioxide, 12 g of carbon is contained.

So, in 18.59 g of carbon dioxide, = $\frac{12}{44}\times 18.59=5.07g$ of carbon will be contained.

For calculating the mass of hydrogen:

In 18g of water, 2 g of hydrogen is contained.

So, in 7.759 g of water, = $\frac{2}{18}\times 7.759=0.862g$ of hydrogen will be contained.

Mass of C = 5.07 g

Mass of H = 0.862 g

Step 1 : convert given masses into moles.

Moles of C = $\frac{\text{ given mass of C}}{\text{ molar mass of C}}= \frac{5.07g}{12g/mole}=0.422moles$

Moles of H= $\frac{\text{ given mass of H}}{\text{ molar mass of H}}= \frac{0.862g}{1g/mole}=0.862moles$

Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated.

For C = $\frac{0.422}{0.422}=1$

For H = $\frac{0.862}{0.422}=2$

The ratio of C : H = 1: 2

Hence the empirical formula is $CH_2$ .

The empirical weight of $CH_2$ = 1(12)+2(1)= 14 g.

The molecular weight = 56.1 g/mole

Now we have to calculate the molecular formula.

$n=\frac{\text{Molecular weight }}{\text{Equivalent weight}}=\frac{56.1}{14}=4$

The molecular formula will be= $4\times CH_2=C_4H_8$

6 0

3 years ago

Why the recombinant DNA is reintroduced into the bacterium?

Doss [256]

Bacterial cells can pick up the DNA through the process of transformation. Lambda phages are used by eliminating the middle of its liner genome and adding the foreign DNA in the created space. The phage is then introduced into the bacterial cell where it replicated itself via the lysogenic cycle.

8 0

3 years ago

Pure substance can be __ and __

Aleksandr [31]

It can be an element or a compound

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3 years ago

Element Q has an atomic number 68. Consider the isotope Q-136 how many protons are in a neutral atom of this isotope?

mote1985 [20]

Answer: 68

Explanation:

Isotopes of an element have same number of protons but different number of neutrons. Which means isotopes of an element have same atomic number but different mass number.

Atomic number is equal to the number of protons or the number of electrons for a neutral atom and is specific to a particular element.

Mass number is the sum of number of protons and the number of neutrons.

Given : atomic number of element Q = 68 = number of protons

Mass number of isotope Q-136 = 136

But as isotopes have same atomic number, the number of protons will be same and hence there are 68 protons are in a neutral atom of this isotope.

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3 years ago

Primary needs in South Africa and secondary needs and wants in South Africa<br>

leonid [27]

Answer:

Food, safe water, housing, education, and health care are examples of basic needs. Wants are desires that can be satisfied by goods and services.Secondary needs are the desires and wants that become important when primary needs are satisfied. Definition (2): Secondary needs are connected with the desire for satisfaction and pleasure of the human being: designer articles or furniture, the high-tech and the newest cell phone, jewelry, a luxury car, etc.

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2 years ago