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3 years ago

Can a physical change, change what a substance is? Exp

1 answer:

7 0

Physical changes are changes affecting the form of a chemical substance, but not its chemical composition. Physical changes are used to separate mixtures into their component compounds, but can not usually be used to separate compounds into chemical elements or simpler compounds.

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An unknown substance has been shown to have metallic bonds.

gladu [14]

This is the correct answer please mark me as brainliest

6 0

3 years ago

Read 2 more answers

1) When 2.38g of magnesium is added to 25.0cm of 2.27 M hydrochloric acid, hydrogen gas is released.

Andrej [43]

Answer:

a. HCl.

b. 0.057 g.

c. 1.69 g.

d. 77 %.

Explanation:

Hello!

In this case, since the reaction between magnesium and hydrochloric acid is:

$Mg+2HCl\rightarrow MgCl_2+H_2$

Whereas there is 1:2 mole ratio between them.

a) Here, we can identify the limiting reactant as that yielded the fewest moles of hydrogen gas product via the 1:1 and 2:1 mole ratios:

$n_{H_2}^{by\ HCl}=0.025L*2.27\frac{molHCl}{1L}*\frac{1molH_2}{2molHCl} =0.0284molH_2\\\\n_{H_2}^{by\ Mg}=2.38gMg*\frac{1molMg}{24.3gMg}*\frac{1molH_2}{1molMg}=0.0979molH_2$

Thus, since hydrochloric yields fewer moles of hydrogen than magnesium, we realize it is the limiting reactant.

b) Here, we use the molar mass of gaseous hydrogen (2.02 g/mol) to compute the mass:

$m_{H_2}=0.0284molH_2*\frac{2.02gH_2}{1molH_2}=0.057gH_2$

c) Here, we compute the mass of magnesium associated with the yielded 0.0248 moles of hydrogen:

$m_{Mg}^{reacted}=0.0284molH_2*\frac{1molMg}{1molH_2}*\frac{24.3gMg}{1molMg} =0.690gMg$

Thus, the mass of excess magnesium turns out:

$m_{Mg}^{excess}=2.38g-0.690g=1.69gMg$

d) Finally, we compute the percent yield, considering 0.044 g is the actual yield and 0.057 g the theoretical yield:

$Y=\frac{0.044g}{0.057g} *100\%\\\\Y=77\%$

Best regards!

8 0

3 years ago

What's the definition if blood

ANEK [815]

Blood is a liquid substance flowing through the arteries and veins of the body. In a healthy normal person, approximately 45% of their blood volume are cells (mostly red blood cells, white blood cells and platelets).

hope this helps!

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3 years ago

Intermolecular forces dipole differences london dispersion

loris [4]

33233728793278237876548742787874578378572098-2932-=93788784787489

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2 years ago

Las Vegas, Nevada is in a desert. How does its rapid population growth affect the

Scrat [10]

Answer:

Many areas of the United States experience explosive population growth. The more people that reside someplace, the more demand there is for water there. Often these urban-growth expansions are unplanned and place extraordinary stress on the water supply system, mainly on the groundwater. The stress often depletes groundwater supply, thereby causing wells to dry up. Then water must be brought from somewhere else to support the local population.

Such situations have occurred all over the United States. For example, increased population growth in the southwestern United States has significantly lowered the water table 50 to 200 feet (depending on the area) since the 1940s. Managing urban growth, efforts to reduce water demand, conservation of the resource, and attempts to increase the water supply all address the problem of exceeding water resource limits.

Human activities affect groundwater quality.

Here are some sources and possible solutions to groundwater pollution:

Agriculture—Reduce usage of pesticides and fertilizers.

Landfills—Monitor for leakage and repair linings.

Underground storage tanks—Remove damaged and unused tanks.

Household wastes—Properly dispose of household hazardous waste.

Septic tank leaks—Properly maintain and repair tanks.

Explanation:

This came from the K12 learning course read this and the answer will be there. I underlined the important parts for the answer.

7 0

3 years ago