Which expression gives the standard enthalpy change of formation for methanol?

Which of the following is an exothermic reaction?

agasfer [191]

The answer is B) an explosion

An exothermic reaction is a chemical reaction that is caused by heat and light.

Have a good day! =)

6 0

4 years ago

In the reaction of an acid with water, a hydronium ion forms

Nutka1998 [239]

Really, ionization takes place. It means the acid dissociates in water. Ionization is just a fancy way of saying dissociation. Always think easy.

Definition of IONIZATION: The process describing the dissociation of an acid in water.

If it ionizes or dissociates completely in water, then it shows that hydronium is a STRONG ACID. And if it ionizes partially, that shows hydronium is a WEAK ACID.

So, the answer will be choice B. by a process called ionization

4 0

4 years ago

Correct answer gets brainliest

sweet-ann [11.9K]

Answer:

e,b and d

Explanation:

5 0

3 years ago

Read 2 more answers

A sample of tin (Cp = 0. 227 J/gâ€˘Â°C) is placed in a freezer. Its temperature decreases from 15. 0Â°C to â’10. 0Â°C as it rele

pshichka [43]

Taking into account the definition of calorimetry, the mass of the sample is 478.41 grams.

Calorimetry is the measurement and calculation of the amounts of heat exchanged by a body or a system.

Sensible heat is defined as the amount of heat that a body absorbs or releases without any changes in its physical state (phase change).

So, the equation that allows to calculate heat exchanges is:

Q = c× m× ΔT

where Q is the heat exchanged by a body of mass m, made up of a specific heat substance c and where ΔT is the temperature variation.

In this case, you know:

Q= -543 J because the energy is releases
c= 0.227 $\frac{J}{gC}$
m= ?
ΔT= Tfinal - Tinitial= 10 C - 15 C= -5 C

Replacing:

-543 J= 0.227 $\frac{J}{gC}$ × m× (-5 C)

Solving:

$m=\frac{-543 J}{0.227 \frac{J}{gC}x(-5 C)}$

m=478.41 grams

In summary, the mass of the sample is 478.41 grams.

Learn more about calorimetry:

4 0

3 years ago

. Citric acid, which can be obtained from lemon juice, has the molecular formula C6H8O7. A 0.250-g sample of citric acid dissolv

marysya [2.9K]

Answer:

3 acidic hydrogens per molecule of citric acid

Explanation:

In a sample of 37.2 mL(0.0372 L) of 0.105 mol/L of NaOH, will have:

n = 0.105x0.0372 = 0.0039 mol of NaOH

The dissociation of NaOH will give the same number of moles of Na⁺ and OH⁻.

The molar mass of citric acid is:

C: 12g/mol x 6 = 72 g/mol

H: 1g/mol x 8 = 8g/mol

O: 16 g/mol x 7 = 112 g/mol

192 g/mol

So, 0.250g of the acid has

n = mass/molar mass

n = 0.250/192

n = 0.0013 mol.

To be neutralized, it will be necessary 0.0039 mol of acidic hydrogens to react with the 0.0039 mol of OH⁻.

The dissociation reaction of one molecule of the acid will give the stoichiometry:

1 mol of acid ----------------------- x mol of acidic hydrogens

0.0013 mol --------------------------- 0.0039

For a simple direct three rule:

0.0013x = 0.0039

x = 3 acidic hydrogens per molecule of citric acid.

3 0

4 years ago