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Romashka-Z-Leto [24]
3 years ago
8

Which choice contains a FALSE statment? A. For the vaporization of liquid benzene ΔH is positive. B. For the formation of 1 mol

nitrogen dioxide from its elements (heat is absorbed)ΔH is negative. C. For the sublimation of dry ice [conversion of CO₂(s) directly to CO₂(g)] ΔH is positive. D. For the reaction of 1 mol of sulfur dioxide with oxygen ΔH is negative. E. None of these is/are FALSE
Chemistry
1 answer:
ser-zykov [4K]3 years ago
7 0

Answer:

B is False

Explanation:

In physical chemistry we always look from system's perspective, so if we heat something ΔH is positive and if the system gives heat out then ΔH is negative.

A. We have to give energy to benzene to evaporate it. Statement true.

B. If heat is absorbed then the enthalpy must be positive.

C. The heat is absorbed then ΔH is positive.

D. Usually for burning heat is exposed from system. So enthalpy is negative.

E. Obvious

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Suppose that 33.3 J of heat is added to an ideal gas. The gas expands at a constant pressure of 1.45 104 Pa while changing its v
levacccp [35]

Answer:

ΔU = 25.8 J

Explanation:

The gas absorbs 33.3 J of heat, that is, Q = 33.3 J.

The work (W) of expansion can be calculated using the following expression:

W = -P. ΔV

where,

P is the external pressure

ΔV is the change in volume

W = -1.45 × 10⁴ N . m⁻² × (8.40 × 10⁻⁴ m³ - 3.24 × 10⁻⁴ m³) = -7.48 J

The change in the internal energy (ΔU) is:

ΔU = Q + W

ΔU =  33.3 J + (-7.48 J) = 25.8 J

5 0
3 years ago
What is the empirical formula of a compound composed of 3.25% hydrogen ( H ), 19.36% carbon ( C ), and 77.39% oxygen ( O ) by ma
Montano1993 [528]

Answer:

The answer to your question is C₂HO₃

Explanation:

Data

Hydrogen = 3.25%

Carbon = 19.36%

Oxygen = 77.39%

Process

1.- Write the percent as grams

Hydrogen = 3.25 g

Carbon = 19.36 g

Oxygen = 77.39 g

2.- Convert the grams to moles

                     1 g of H ----------------- 1 mol

                   3,25 g of H -------------  x

                     x = (3.25 x 1) / 1

                     x = 3.25 moles

                    12 g of C ---------------- 1 mol

                     19.36 g of C ----------  x

                     x = (19.36 x 1) / 12

                     x = 1.61 moles

                     16g of O --------------- 1 mol

                     77.39 g of O ---------  x

                      x = (77.39 x 1)/16

                      x = 4.83

3.- Divide by the lowest number of moles

Carbon = 3.25/1.61 = 2

Hydrogen = 1.61/1.61 = 1

Oxygen = 4.83/1.61 = 3

4.- Write the empirical formula

                        C₂HO₃

4 0
3 years ago
The sum of the protons and neutrons in an atom is called the atomic number <br> True or False
olganol [36]
It is false, the atomic number is the number of protons and/or electrons in an atom on an element.
3 0
3 years ago
when using a clamp and ring stand to hold glassware and tools, what is the best position for the clamp?
lora16 [44]
The bottom







Explanation:
4 0
3 years ago
Sodium acetate can be formed from the metathesis/double replacement reaction of sodium
telo118 [61]

Answer:

Explanation:

Sodium Acetate Trihydrate BP Specifications

Sodium Acetate BP

C2H3NaO2,3H2O

Action and use

Used in solutions for dialysis; excipient.

DEFINITION

Sodium ethanoate trihydrate.

Content

99.0 per cent to 101.0 per cent (dried substance).

CHARACTERS

Appearance

Colourless crystals.

Solubility

Very soluble in water, soluble in ethanol (96 per cent).

IDENTIFICATION

A. 1 ml of solution S (see Tests) gives reaction (b) of acetates.

B. 1 ml of solution S gives reaction (a) of sodium.

C. Loss on drying (As shown in the Relevant Test).

TESTS

Solution S

Dissolve 10.0 g in carbon dioxide-free water prepared from distilled water R and dilute to 100 ml 100 ml with the same solvent.

Appearance of solution

Solution S is clear and colourless.

pH

7.5 to 9.0.

Dilute 5 ml of solution S to 10 ml with carbon dioxide-free water.

Reducing substances

Dissolve 5.0 g in 50 ml of water, then add 5 ml of dilute sulphuric acid and 0.5 ml of 0.002 M potassium permanganate. The pink colour persists for at least 1 h. Prepare a blank in the same manner but without the substance to be examined.

Chlorides

Maximum 200 ppm.

Sulphates

Maximum 200 ppm.

Aluminium

Maximum 0.2 ppm, if intended for use in the manufacture of dialysis solutions.

Arsenic

Maximum 2 ppm, determined on 0.5 g.

Calcium and magnesium

Maximum 50 ppm, calculated as Ca.

Heavy metals

Maximum 10 ppm.

Iron

Maximum 10 ppm, determined on 10 ml of solution S.

Loss on drying

39.0 per cent to 40.5 per cent, determined on 1.000 g by drying in an oven at 130C.

Sodium Acetate FCC Food Grade, US Food Chemical Codex

C2H3NaO2 Formula wt, anhydrous 82.03

C2H3NaO2·3H2O Formula wt, trihydrate 136.08

DESCRIPTION

Sodium Acetate occurs as colorless, transparent crystals or as a granular, crystalline or white powder. The anhydrous form is hygroscopic; the trihydrate effloresces in warm, dry air. One gram of the anhydrous form dissolves in about 2 mL of water; 1 g of the trihydrate dissolves in about 0.8 mL of water and in about 19 mL of alcohol.

Function: Buffer.

REQUIREMENTS

Identification: A 1:20 aqueous solution gives positive tests for Sodium and for Acetate.

Assay: Not less than 99.0% and not more than 101.0% of C2H3NaO2 after drying.

Alkalinity Anhydrous: Not more than 0.2%; Trihydrate: Not more than 0.05%.

Lead: Not more than 2 mg/kg.

Loss on Drying: Anhydrous: Not more than 1.0%; Trihydrate: Between 36.0% and 41.0%.

Potassium Compounds: Passes test.

5 0
3 years ago
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