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3 years ago

J.

Chemistry

2 answers:

Ahat [919]3 years ago

4 0

Answer:

The line of sight must be perpendicular to measuring scale to avoid parallax error. Formation of bubbles inside the cylinder should be completely avoided.

Explanation:

snow_tiger [21]3 years ago

4 0

Answer:

Here is your answer : )

Explanation:

these are precautions

The line of sight must be perpendicular to measuring scale to avoid parallax error. Formation of bubbles inside the cylinder should be completely avoided

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Identify which result of a physical rather than a chemical change

Pani-rosa [81]

Explanation:

A physical change is change that alters the physical properties of matter especially its form and state.

In many cases, the change is easily reversible.

Examples are change of state such as boiling, melting, freezing, condensation, sublimation e.t.c

A chemical change is one in which a new kind of matter is formed. It is always accompanied by energy changes.

Examples are combustion, rusting , precipitation, milk souring.

Chemical changes are irreversible
Physical changes do not lead to the formation of new kinds of matter.
Most physical changes requires little energy.

You can use this knowledge to solve your problem

learn more:

Chemical change brainly.com/question/9388643

#learnwithBrainly

8 0

4 years ago

Label each of the descriptions below as theoretical

anzhelika [568]

Answer:

Before performing chemical reactions, it is helpful to know how much product will be produced with given quantities of reactants. This is known as the theoretical yield. This is a strategy to use when calculating the theoretical yield of a chemical reaction. The same strategy can be applied to determine the amount of each reagent needed to produce a desired amount of product.

Explanation:

Reagent Examples

Reagents may be compounds or mixtures. In organic chemistry, most are small organic molecules or inorganic compounds. Examples of reagents include Grignard reagent, Tollens' reagent, Fehling's reagent, Collins reagent, and Fenton's reagent. However, a substance may be used as a reagent without having the word in its name.

3 0

3 years ago

Read 2 more answers

Find the pH of the equivalence point and the volume (mL) of 0.0372 M NaOH needed to reach the equivalence point in the titration

elixir [45]

Answer:

8.54

Explanation:

At equivalence point :

42.2 X 0.052 = Vol. NaOH X 0.0372

Vol of NaOH = 2.1944/0.0372 = 58.99 ml

So volume of NaOH recquired to reach equivalence point = 58.99 ml

Number of miliimoles of CH3COOH = molarity X volume in ml = 42.2 X 0.052 = 2.1944 millimoles

Number of millimoles of NaOH = 58.99 X 0.0372 = 2.1944

Now CH₃COOH and NaOH reacts to give CH₃COONa according to the reaction :

CH₃COOH + NaOH ------> CH₃COONa + H₂O

1 mole of CH₃COOH reacts with 1 mole of NaOH to give 1 mole of CH₃COONa

So 2.1944 millimoles of CH₃COOH will react with 2.1944 millimoles of NaOH to give 2.1944 millimoles of CH₃COONa

So all the acid (CH₃COOH) and base (NaOH) has been converted into salt (CH₃COONa) so there is no acid or base left.

Now molarity of CH₃COONa = number of millimoles of CH₃COONa/total volume in ml = 2.1944/(58.99 + 42.2) = 2.1944/101.19 = 0.02169 M

So using the hydrolysis equation :

pH = 1/2 [ pKw + pKa + log c ]

Ka for acetic acid = 1.75 X 10⁻⁵

so pKa = -log (1.75 X 10⁻⁵) = 4.74

Kw = 10⁻¹⁴

so pKw = -log 10⁻¹⁴ = 14

c = 0.02169

so log c = log 0.02169 = -1.66

putting the values....

pH = 1/2 [14 + 4.74 - 1.66 ]

pH = 1/2 [ 17.08] = 8.54

6 0

3 years ago

Read 2 more answers

1. Pewien tlenek azotu o masie cząsteczkowej 108 u zawiera 74,07% tlenu. Wykonaj stosowne obliczenia i napisz wzór sumaryczny te

love history [14]

Answer:

1. Stąd empiryczny wzór substancji to N₂O₅

2. W związku z tym ilość w gramach chlorku sodu NaCl is 114,4 g.

Explanation:

1. Mamy tutaj;

Masa molowa tlenku azotu = 108u

Masa azotu = 14,0067u

Masa tlenu = 15,999 u

74,07% masy tlenku azotu to tlen

Dlatego masa obecnego tlenu = 108 × 74,07 / 100 = 79,9956 u

Masa obecnego azotu = 108 - 79,9956 = 28,0044u

Liczba moli tlenu = 79,9956 / 15,999 = 5,00003 ≈ 5

Liczba moli azotu = 28,0044 / 14,0067 = 1,99935 ≈ 2

Stąd empiryczny wzór substancji to N₂O₅.

2. Kiedy sód reaguje z chlorem, mamy;

2Na (s) + Cl₂ (g) → 2NaCl (s)

Dlatego 2 mole sodu Na reaguje z 1 molem chloru gazowego Cl₂, z wytworzeniem 2 moli chlorku sodu NaCl

W związku z tym 1 mol sodu Na reaguje z 1/2 molem chloru gazowego Cl₂ z wytworzeniem 1 mola chlorku sodu NaCl

Masa Na obecnego w reakcji = 45 g

Masa molowa sodu = 22,989769u

Liczbę moli sodu w 45 g sodu podano w następujący sposób;

$Liczba \, \, moli \, \, Na= \frac{Mass \, of \, Na}{Molowy \, masa \, z \, Na} = \frac{45}{22.989769} = 1.96 \, mole$

Z czego 1,96 moli sodu Na reaguje z 1/2 × 1,96 mola chloru gazowego Cl₂ z wytworzeniem 1,96 mola chlorku sodu NaCl

Masa molowa NaCl = 58,44 g / mol

Dlatego masa NaCl = liczba moli NaCl × masa molowa NaCl

Masa NaCl = 1,96 × 58,44 = 114,39001 g ≈ 114,4 g

W związku z tym ilość w gramach chlorku sodu NaCl = 114,4 g.

4 0

3 years ago

What are the masses of the four different BrClBrCl molecules? Express the masses in atomic mass units using six significant figu

Sliva [168]

Answer ; The question is missing in some details, but here are he details ;

The two naturally occurring isotopes of bromine are

81Br (80.916 amu, 49.31%) and

79Br (78.918 amu, 50.69%).

The two naturally occurring isotopes of chlorine are

37Cl (36.966 amu, 24.23%) and

35Cl (34.969 amu, 75.77%).

Bromine and chlorine combine to form bromine monochloride, BrCl.

Explanation:

The detaile calculation is as shown in the attachment.

6 0

3 years ago