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gavmur [86]
3 years ago
11

Which of these would remove water from a river?

Chemistry
1 answer:
mariarad [96]3 years ago
5 0

Dams fail. It’s inevitable and it’s happening now.

Flooding of the Waccamaw River at Pitch Landing SC thanks to Hurricane Matthew. | Laila Johnston

Flooding of the Waccamaw River at Pitch Landing, SC thanks to Hurricane Matthew. | Laila Johnston

Just recently, Hurricane Matthew caused widespread flooding and more than 20 dam failures in North and South Carolina.

Rewind one year to October 2015— same place, different storm. One out of every 50 dams regulated by the State of South Carolina failed (plus hundreds of unregulated dams). This was the second most costly environmental disaster in South Carolina’s history — $12 billion. And more devastating than the financial cost is the loss of life (so far 59 people in the U.S. between the two storms) and destruction of homes and businesses (more than 1 million structures destroyed in Hurricane Matthew).

Fast forward to early October 2016, thousands of people have been evacuated from their homes due to the threat of dam failures in North Carolina. Plugging a hole the size of a truck will require more than a little duct tape.

Part of the problem is that we aren’t thinking ahead. Many dams look very formidable. Big walls. Strong. But concrete breaks down over time, especially when subject to the forces of nature. So does brick and mortar. And earthen dams? No doubt.

We need a commonsense approach to managing our infrastructure.

WHY DO DAMS FAIL?

Penobscot River | PRRT

Veazie Dam breach on the Penobscot River, ME

Dam failure can result from any number of issues, including: inadequate spillway design, spillways blocked by debris causing dam overtopping, land use change causing increased runoff, outdated technology and design, changing weather patterns that alter flow rates, defects in the dam’s foundation, settlement of the dam crest, internal erosion of the dam caused by seepage (this can happen around pipes, animal burrows, plant roots, other cracks), structural failure of the materials used in dam construction, and/or inadequate maintenance of the structure.

Dams are deteriorating faster than they can be repaired. According to the Association of State Dam Safety Officials, the cost to rehabilitate our nation’s dams would be more than $70 billion (high hazard dams alone would cost $18.2 billion to rehabilitate).

[clickToTweet tweet=”According to @Dam_Safety, it’d take $51 billion to rehabilitate nonfederal dams in US. ” quote=”According to the Association of State Dam Safety Officials, it would take an estimated $51.46 billion to rehabilitate the nation’s non-federal dams. “]

Meanwhile, state dam safety offices are historically underfunded with a limited number of staff responsible for inspecting hundreds of dams. This tends to result in a focus on only those larger structures that pose a higher risk to life and public and private property should they fail. Smaller structures may be inspected infrequently, if at all, creating a threat to public safety. While many of these dams are “low hazard,” that is not the same as no hazard. Failure of small dams has been known to wreak environmental damage and cause significant downstream damage to things like driveways or roads.

There are also social behavior issues surrounding dams, which confound safety concerns. People seem to love to play on, in, and around dams. Paddling, fishing, swimming, sunbathing. It all seems fun until you get sucked into the hydraulic undertow.

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The left atrium does that
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3 years ago
Identify the component required for the electrolysis of molten nacl
EleoNora [17]
The components required for the electrolysis of molten NaCl are a source of electrical energy such as a battery and electrodes (anode and cathode). Electrolysis is the process of decomposing and electrolyte (either and aqueous solution or molten solution) by passing an electric current through it. During electrolysis the positive ion moves to the negatively charged electrode (cathode), while the negatively charged ions go to the anode.
4 0
3 years ago
Calculate the following:<br> 36,000 nanograms =<br> micrograms
Alenkinab [10]
36 micrograms is the answer
7 0
3 years ago
Percent of water in Na2CO3 • 10H2O
Troyanec [42]
Hey there! 

In order to solve for the percentage of water in the compound, you will first need to find its total molar mass. You can do this by adding up the molar masses of each individual element in the compound. Then, you will divide the mass that you find of the water molecules by the total mass to get the percentage. 

→ Na₂CO₃ ×<span> 10 H</span>₂<span>O

</span>→ Na₂ = 22.9898 × 2 = 45.9796
→ C = 12.0107
→ O₃ = 15.999 × 3 = 47.997
→ 10 H₂O = 18.015 × 10 = 180.15

Now, just add all of those numbers up for the total molar mass. 

→ 45.9796 + 12.0107 + 47.997 + 180.15 = <span>286.1373
</span>
The last step is to divide the molar mass of the 10 water molecules by the total mass. 

→ 180.15 ÷ 286.1373 = <span>0.62959 </span>≈ 0.63

Your answer will be about 63%. 

Hope this helped you out! :-)
5 0
3 years ago
A 150.0 mL solution of 2.888 M strontium nitrate is mixed with 200.0 mL of a 3.076 M sodium fluoride solution. Calculate the mas
Lelechka [254]

Answer:

Mass SrF2 produced = 38.63 g SrF2 produced

[Na^+]:  = 1.758 M

[NO3^-]:  = 1.238 M

[Sr^2+] = 0.3589 M

[F^-] = 2.36*10^-5 M

Explanation:

Step 1: Data given

Volume of 2.888M strontium nitrate = 150.0 mL = 0.150 L

Volume of 3.076 M sodium fluoride = 200.0 mL = 0.200 L

Step 2 : The balanced equation

Sr(NO3)2(aq) + 2NaF(aq) → SrF2(s) + 2NaNO3(aq) → Sr2+ + 2F- + 2

Step 3: Calculate moles strontium nitrate

Moles Sr(NO3)2 = Molarity * volume  

Moles Sr(NO3)2 = 2.888 M * 0.150 L

Moles Sr(NO3)2 = 0.4332 moles

Step 4: Calculate moles NaF

Moles NaF = 3.076 M * 0.200 L

Moles NaF = 0.6152 moles

It takes 2 moles F^- to precipitate 1 mole Sr^2+, so F^- is limiting.

Step 5: Calculate limiting reactant

For 1 mol of Sr(NO3)2 we need 2 moles of NaF to produce 1 mol of SrF2 and 2 moles of NaNO3

NaF is the limiting reactant. It will completely be consumed (0.6152 moles).

Sr(NO3)2 is in excess. There will react 0.6152/2 = 0.3076 moles

Moles Sr^2+ precipitated by F^- = 0.3076

There will remain 0.4332 - 0.3076 = 0.1256 moles of Sr(NO3)2

Moles Sr^2+ no precipitated (left over) = 0.1256 moles

Step 6: Calculate moles SrF2  

For 1 mol of Sr(NO3)2 we need 2 moles of NaF to produce 1 mol of SrF2 and 2 moles of NaNO3

For 0.6152 moles NaF we have 0.6152/2 = 0.3076 moles of SrF2

Mass SrF2 produced:  0.3076 mol * 125.6 g/mol = 38.63 g SrF2 produced

Step 7: Calculate concentration of [Na+] and [NO3-]

Since both Na^+ and NO3^- are spectator ions, and the final volume is 150 ml + 200 ml = 350 ml (0.350 L), the concentrations of Na^+ and NO3^- can be calculated as follows:

[Na^+]:  (200 ml)(3.076 M) = (350 ml)(x M) and x = 1.758 M

[NO3^-]:  (150 ml)(2.888 M)(2) = (350 ml)(x M) = 1.238 M

Step 8: Calculate [Sr^2+] and [F^-]

[Sr^2+] = 0.1256 moles/0.350 L = 0.3589 M

To find [F^-], one needs the Ksp for SrF2.  There are several values listed in the literature. I am using a value of 2x10^-10.

SrF2(s) <==> Sr^2+(aq) + 2F^-(aq)

Ksp = [Sr^2+][F^-]²

2x10^-10 = (0.3589)(x)²

x² = 5.57*10^-10

x = [F^-] = 2.36*10^-5 M

4 0
3 years ago
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