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3 years ago

Which events represents a chemical change ?

Chemistry

2 answers:

8_murik_8 [283]3 years ago

5 0

D milk turning sour
the other options are physical changes

yawa3891 [41]3 years ago

3 0

Hihi!

The answer would be D. milk turning sour! What happens when milk goes sour is it ferment lactose at room temperature and which turns it into lactic acid. More acid means more hydrogen ions, a lower pH and a sour taste. Lower pH change the structure of proteins like casein, which gives milk its whiteness, so it curdles into clumps called curds! It's pretty gross!

I hope I helped!
-Jailbaitasmr

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mote1985 [20]

Carbon Dioxide with water and sunlight produce glucose and oxygen

4 0

4 years ago

Do you think creativity can contribute to scientific inquiry and investigation?

Firdavs [7]

Yes. It is only through creativity that scientific inquiry exists. Someone had the wacky creative idea that there should be something that is so strong, and inflammable, and just generally amazing like a super... thing! And tadaaah, we have Kevlar. The stuff in bullet proof vests.

3 0

3 years ago

Determine the enthalpy of neutralization in Joules/mmol for a solution resulting from 19 mL of 0.9 M NaOH solution and 19 mL of

Rina8888 [55]

Answer:

3.00 J/mmol

Explanation:

The temperature of the solution is increasing, so it's an endothermic reaction. The heat that is being absorbed can be calculated by:

Q = m*c*ΔT

Where m is the total mass (HCl + NaOH), c is the specific heat, and ΔT is the variation of the temperature (final - initial). Because the molarity is small, the solutions are basically water, so c = 4.184 J/g°C.

The mass is the molar mass multiplied by the number of moles (n), which is the volume multiplied by the molarity:

nHCl = 0.9 mol/L *0.019 = 0.0171 mol

nNaOH = 0.9 mol/L *0.019 = 0.0171 mol

Molar masses: HCl = 36.5 g/mol; NaOH = 40 g/mol

mHCl = 36.5*0.0171 = 0.62415 g

mNaOH = 40 * 0.0171 = 0.6840 g

m = 1.30815 g

Q = 1.30815*4.184*(37.8 - 28.8)

Q = 49.2597 J

Because the number of moles of NaOH is equal to the number of moles of HCl, and the stoichiometry of the neutralization is 1:1, they both react completely, so the enthalpy can be calculated based in any of them. The enthalpy is the heat divided by the number of moles. In mmol, n is 17.1 mmol.

ΔH = 49.2597/17.1

ΔH = 2.88 J/mmol

ΔH = 3.00 J/mmol

7 0

3 years ago

(a) show that the pressure exerted by a fluid P (in pascals) is given by P= hdg, where h is the column of the fluid in metres, d

Murrr4er [49]

Answer:

56.4 m

Explanation:

volume increases by factor of 6, i.e $\frac{V2}{V1}$ = 6

Initial temperature T1 at bottom of lake = 5.24°C = 278.24 K

Final temperature T2 at top of lake = 18.73°C = 291.73 K

NB to change temperature from °C to K we add 273

Final pressure P2 at the top of the lake = 0.973 atm

Initial pressure P1 at bottom of lake = ?

Using the equation of an ideal gas

$\frac{P1V1}{T1}$ = $\frac{P2V2}{T2}$

P1 = $\frac{P2V2T1}{V1T2}$ = $\frac{0.973*6*278.24}{291.73}$

P1 = 5.57 atm

5.57 atm = 5.57 x 101325 = 564380.25 Pa

Density Ρ of lake = 1.02 g/ $cm^{3}$ = 1020 kg/ $m^{3}$

acceleration due to gravity g = 9.81 $m/s^{2}$

Pressure at lake bottom = pgd

where d is the depth of the lake

564380.25 = 1020 x 9.81 x d

d = $\frac{564380.25}{10006.2}$ = 56.4 m

3 0

4 years ago

In the presence of oxygen, the three-carbon compound pyruvate can be catabolized in the citric acid cycle. First, however, the p

Flura [38]

Answer:1.

Explanation: This reaction is catalyzes by pyruvate dehydrogenase. Pyruvate being the end product of glycolysis has many fates after glycolysis,one of which is to enter the TCA(Tricarboxylic acid cycle) cycle. It is first converted to actetate by the action of pyruvate dehydrogenase. This enzyme converts pyruvate to acetate releasing CO2 and NADH because this oxidative decarboxylation of pyruvate is coupled with reduction of NAD+ which can feed into the electron transport chain.

6 0

3 years ago