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2 years ago

What is exothermic and endothermic? How do they differ?

1 answer:

6 0

Exothermic releases energy(heat) from the system to the surrounding
endothermic takes energy (heat) from the surrounding to the system

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Grace wanted to find out the best conditions for growing lettuce plants.

Mariana [72]

Explanation:

the investigation lasts for 7 days !

hope this helps you.

8 0

2 years ago

The mole fraction of CO2 in a certain solution with H2O as the solvent is 3.6 × 10−4. What is the approximate molality of CO2 in

nataly862011 [7]

Answer: C) 0.020 m

Explanation:

Molality of a solution is defined as the number of moles of solute dissolved per kg of the solvent.

$Molality=\frac{n\times 1000}{W_s}$

where,

n = moles of solute

$W_s$ = weight of solvent in g

Mole fraction of $CO_2$ is = $3.6\times 10^{-4}$ i.e. $3.6\times 10^{-4}$ moles of $CO_2$ is present in 1 mole of solution.

Moles of solute $(CO_2)$ = $3.6\times 10^{-4}$

moles of solvent (water) = 1 - $3.6\times 10^{-4}$ = 0.99

weight of solvent = $moles\times {\text {Molar mass}}=0.99\times 18=17.82g$

Molality = $\frac{3.6\times 10^{-4}\times 1000}{17.82g}=0.020$

Thus approximate molality of $CO_2$ in this solution is 0.020 m

5 0

3 years ago

The ka values for several weak acids are given below. which acid (and its conjugate base) would be the best buffer at ph = 8.0?

Pie

One of the best buffer choice for pH = 8.0 is Tris with Ka value of 6.3 x 10^-9.

To support this answer, we first calculate for the pKa value as the negative logarithm of the Ka value:
pKa = -log Ka

For Tris, which is an abbreviation for 2-Amino-2-hydroxymethyl-propane-1,3 -diol and has a Ka value of 6.3 x 10^-9, the pKa is
pKa = -log Ka
= -log (6.3x10^-9)
= 8.2

We know that buffers work best when pH is equal to pKa:
pKa = 8.2 = pH

Therefore Tris would be a best buffer at pH = 8.0.

7 0

3 years ago

Read 2 more answers

a set of pulleys is used to lift a piano weighing 1,000 netwons. the piano is lifted 3 meters in 60 seconds. How much power is u

DENIUS [597]

P = W/t

P = F.s/t

P = 1000.3/60

P = 50 watt

6 0

1 year ago

Read 2 more answers

What product is formed when 1-bromopropane reacts with ch3o−?

STatiana [176]

When 1-Bromopropane is treated with methoxide it undergoes SN² Reaction. The product formed is Methyl Propyl Ether. This type of reaction is very important in synthesizing Asymmetric ethers. The alkoxides are oftenly generated by reacting Alcohols with sodium metal, which on elimination of Hydrogen gas produces corresponding alkoxide. The reaction of given statement is as follow,

4 0

2 years ago