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3 years ago

Write a balanced chemical equation for the following: magnesium metal is burned in oxygen to produce magnesium oxide.

Chemistry

1 answer:

KiRa [710]3 years ago

8 0

Answer:

2Mg (s) + $O_{2}$ (g) ---> 2MgO (s)

Explanation:

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A solution of an unknown nonvolatile nonelectrolyte was prepared by dissolving 0.250 g of the substance in 40.0 g of ccl4. the b

Finger [1]

Answer : The molar mass of the solute will be 87.90 g/mol.

Explanation : We know the formula for elevation in boiling point, which is

Δt = i $K_{b}$ m

given that, Δt = 0.357, $K_{b}$ = 5.02 and mass of $CCl _{4}$ = 40,

on substituting the value we get,
0.357 = (1) X (5.02) X (x/ 0.044), on solving we get x = 2.844 X $10^{-3}$ .
Now, 0.250/ 2.844 X $10^{-3}$ = 87.90 g/mol. which is the weight of unknown component.

3 0

3 years ago

Calculate the number of chlorine atoms that are present in 66.05 g of dichloromethane, ch2cl2. when you have the number, take it

Whitepunk [10]

From the periodic table:
mass of carbon = 12 grams
mass of hydrogen = 1 gram
mass of chlorine = 35.5 grams
Therefore,
molar mass of CH2Cl2 = 12 + 2(1) + 2(35.5) = 85 grams

number of moles = mass / molar mass
number of moles of CH2Cl2 = 66.05 / 85 = 0.777 moles

One mole of CH2Cl2 contains two moles of Cl and each chlorine mole has Avogadro's number of atoms in it.
Therefore,
number of chlorine atoms in 0.777 moles of CH2Cl2 can be calculated as follows:
number of atoms = 0.777 * 2 * 6.022 * 10^23 = 9.358 * 10^23 atoms

Now, we will take log base 10 for this number:
log (9.358 * 10^23) = 23.97119

5 0

3 years ago

Three mixtures were prepared from three very narrow molar mass distribution polystyrene samples with molar masses of 10,000, 30,

8_murik_8 [283]

Answer:

(a). 46,666.7 g/mol; 78,571.4 g/mol

(b). 86950g/mol; 46,666.7 g/mol.

(c). 86950g/mol; 43,333.33 g/mol

Explanation:

So, we are given the molar masses for the three samples as: 10,000, 30,000 and 100,000 g mol−1.

Thus, the equal number of molecule in each sample = ( 10,000 + 30,000 + 100,000 ) / 3 = 46,666.7 g/mol.

The average molar mass = [ ( 10,000)^2 + (30,000)^2 + 100,000)^2] ÷ 10,000 + 30,000 + 100,000 = 78,571. 4 g/mol.

(b). The equal masses of each sample = 3/[ ( 1/ 10,000) + (1/30,000 ) + (1/100,000) ] = 20930.23 g/mol.

Average molar mass = ( 10,000 + 30,000 + 100,000 ) / 3 = 46,666.7 g/mol.

(c). Equal masses of the two samples = (0.145 × 10,000) + (0.855 × 100,000)/ 0.145 + 0.855 = 86950g/mol.

The weight average molar mass = 1.7 + 10,000 + 100,000/ 1.7 + 1 = 43,333.33 g/mol.

6 0

3 years ago

Which of the following is the best definition of convection?

lara [203]

<span>a) movement of heat through space </span>

7 0

3 years ago

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When does cortisol get release by the body ?

Amiraneli [1.4K]

Normally, cortisol is present in the body at higher levels in the morning, and at it is lowest at night. Although stress isn’t the only reason that cortisol is secreted into the bloodstream, it has been termed “the stress hormone” because it’s also secreted in higher levels during the body’s stress response and is responsible for several stress-related changes in the body.

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3 years ago