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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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Identical rock types, identical fossils, and very similar mountain ranges are found on different continents that are separated b

Dmitriy789 [7]

Answer:

These continents were joined together at one time in the past.

Explanation:

Identical rock types, identical fossils, and very similar mountain ranges are found on different continents that are separated by a wide ocean. Which of these BEST explains these observations?

8 0

3 years ago

Read 2 more answers

Which of the following is a combustion reaction?

azamat

Answer:

A.NaOH+HCI+NaCI+H2O

Explanation:

It's a Acid-base

5 0

2 years ago

What is the pressure inside a 2.0 L bottle filled with 0.25 mol of carbon dioxide gas at 25 °C?

motikmotik

Answer:

3.1atm

Explanation:

Given parameters:

Volume of gas = 2L

Number of moles = 0.25mol

Temperature = 25°C = 25 + 273 = 298K

Unknown:

Pressure of the gas = ?

Solution:

To solve this problem, we use the ideal gas equation.

This is given as;

PV = nRT

P is the pressure

V is the volume

n is the number of moles

R is the gas constant = 0.082atmdm³mol⁻¹K⁻¹

T is the temperature

P = $\frac{nRT}{V}$

Now insert the parameters and solve;

P = $\frac{0.25 x 0.082 x 298}{2}$ = 3.1atm

8 0

3 years ago

A student isolated 7.2 g of 1-bromobutane reacting equimolar amounts of 1-butanol (10 ml) and NaBr (11.1 g) in the presence of s

Alla [95]

Answer: The percent yield of the 1-bromobutane is 48.65 %

Explanation:

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ .....(1)

For NaBr:

Given mass of NaBr = 11.1 g

Molar mass of NaBr = 103 g/mol

Putting values in equation 1, we get:

$\text{Moles of NaBr}=\frac{11.1g}{103g/mol}=0.108mol$

The chemical equation for the reaction of 1-butanol and NaBr is:

$\text{1-butanol + NaBr}\rightarrow \text{1-bromobutane}$

By Stoichiometry of the reaction

1 mole of NaBr produces 1 mole of 1-bromobutane

So, 0.108 moles of NaBr will produce = $\frac{1}{1}\times 0.108=0.108$ moles of 1-bromobutane

Now, calculating the mass of 1-bromobutane from equation 1, we get:

Molar mass of 1-bromobutane = 137 g/mol

Moles of 1-bromobutane = 0.108 moles

Putting values in equation 1, we get:

$0.108mol=\frac{\text{Mass of 1-bromobutane}}{137g/mol}\\\\\text{Mass of 1-bromobutane}=(0.108mol\times 137g/mol)=14.80g$

To calculate the percentage yield of 1-bromobutane, we use the equation:

$\%\text{ yield}=\frac{\text{Experimental yield}}{\text{Theoretical yield}}\times 100$

Experimental yield of 1-bromobutane = 7.2 g

Theoretical yield of 1-bromobutane = 14.80 g

Putting values in above equation, we get:

$\%\text{ yield of 1-bromobutane}=\frac{7.2g}{14.80g}\times 100\\\\\% \text{yield of 1-bromobutane}=48.65\%$

Hence, the percent yield of the 1-bromobutane is 48.65 %

5 0

2 years ago

from the following equation in which decomposition of CaCO3 takes place, give your justification. CaCO3 gives Ca +CO2

IceJOKER [234]

Answer:

CaCO₃(s) => CaO(s) + CO₂(g) ... GpIIA Decomp

Explanation:

Metallic Carbonates decompose into a metallic oxide and carbon dioxide.

Examples:

Na₂CO₃(s) => Na₂O(s) + CO₂(g) ... GpIA Decomp

MgCO₃(s) => MgO(s) + CO₂(g) ... GpIIA Decomp

7 0

2 years ago