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3 years ago

See if you can think of a way to prove that it is the oxygen in air, not nitrogen, that causes rusting.

Chemistry

1 answer:

allsm [11]3 years ago

8 0

Answer:

rusting occur in oxygen and water coz when you put a nail into the water and you leave it three days you will the nail become brownish and that is due to oxygen and water

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PLA is a bioplastic that is biodegradable. Explain how is is created and why it is biodegradable.

Ratling [72]

Explanation:

<h3>PLA is a polyester produced by fermentation under controlled conditions of a carbohydrate source like corn starch or sugarcane. ... The starch is then mixed with acid or enzymes and heated. This process “breaks” starch into dextrose (D-glucose), or corn sugar.</h3>

<h3>PLA is a polymer made from high levels of polylactic acid molecules. </h3><h3>For PLA to biodegrade, you must break up the polymer by adding </h3><h3>water to it (a process known as hydrolyzing). Heat and moisture are required for hydrolyzing to occur.</h3>

<h3>PLA consists of renewable raw materials and is biodegradable in industrial composting plants. </h3><h3>However, due to the lack of infrastructure, it is difficult to </h3><h3>compost PLA industrially or to</h3><h3> recycle it.</h3>

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2 years ago

The temperature at which carbon dioxide sublimes is about 195 K. What is this

Rom4ik [11]

This temperature in units of degree Celsius is..

-78° Celsius

3 0

3 years ago

Will a precipitate form from Pb(NO3)2(aq) and HCl(aq)?

Rus_ich [418]

1. Write out the formula Pb(NO3)2 (aq) + 2HCl (aq) ----> PbCl2 + 2HNO3 2. Use solubility guidelines (gotta memorize 'em) for the products to see if a solid forms Nitrates are always soluble so 2HNO3 (aq) Chlorides (Cl) are always soluble except for when you mix them with copper, lead, mercury, or silver. Since you mixed it with lead (Pb) it is solid and forms a precipitate. PbCl2 (s)

5 0

3 years ago

For Na2HPO4:(( (Note that for H3PO4, ka1= 6.9x10-3, ka2 = 6.4x10-8, ka3 = 4.8x10-13 ) a) The active anion is H2PO4- b) The activ

Komok [63]

Answer:

Check the explanation

Explanation:

Answer – Given, $H_3PO_4$ acid and there are three Ka values

$K_{a1}=6.9x10^8, K_{a2} = 6.2X10^8, and K_{a3}=4.8X10^{13}$

The transformation of $H_2PO_4- (aq) to HPO_4^2-(aq)$ is the second dissociation, so we need to use the Ka2 = 6.2x10-8 in the Henderson-Hasselbalch equation.

Mass of KH2PO4 = 22.0 g , mass of Na2HPO4 = 32.0 g , volume = 1.00 L

First we need to calculate moles of each

Moles of KH2PO4 = 22.0 g / 136.08 g.mol-1

= 0.162 moles

Moles of Na2HPO4 = 32.0 g /141.96 g.mol-1

= 0.225 moles

[H2PO4-] = 0.162 moles / 1.00 L = 0.162 M

[HPO42-] = 0.225 moles / 1.00 L = 0.225 M

Now we need to calculate the pKa2

pKa2 = -log Ka

= -log 6.2x10-8

= 7.21

We know Henderson-Hasselbalch equation

pH = pKa + log [conjugate base] / [acid]

pH = 7.21 + log 0.225 / 0.162

= 7.35

The pH of a buffer solution obtained by dissolving 22.0 g of KH2PO4 and 32.0 g of Na2HPO4 in water and then diluting to 1.00 L is 7.35

6 0

3 years ago

A substance has half the number of particles as 12 grams of carbon 12, how many moles are in the substance?

gavmur [86]

the molar mass is how many grams it takes to make a full mole. The number in carbon 12 tells us that it takes 12 g to makes a mole, so one half of that would be <u><em>option d, 0.5</em></u>.

7 0

3 years ago

Read 2 more answers