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Chemical reactions
CaCl2 + Rb2SO4 💧→ CaSO4↓ + 2RbCl

CaCl₂ + Rb₂SO₄ 💧→ CaSO₄↓ + 2RbCl

Last updated: June 13, 2022

Reaction of calcium chloride and rubidium sulfate: CaCl₂Calcium chloride + Rb₂SO₄Rubidium sulfate
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CaSO₄↓Calcium sulfate + 2RbClRubidium chloride

The reaction of calcium chloride and rubidium sulfate yields calcium sulfate and rubidium chloride. This reaction is an acid-base reaction and is classified as follows:

Precipitation reaction

Table of contents

Reaction data

Reactants

Chemical formula	Name	Coefficient	Type	Type in general equation
CaCl₂	Calcium chloride	1	Lewis acid	Very soluble in water
Rb₂SO₄	Rubidium sulfate	1	Lewis base	Very soluble in water

Products

Chemical formula	Name	Coefficient	Type	Type in general equation
CaSO₄	Calcium sulfate	1	Lewis conjugate	Slightly soluble in water
RbCl	Rubidium chloride	2	Non-redox product	–

Thermodynamic changes

Changes in standard condition (1)

Reaction of calcium chloride and rubidium sulfate ◆ Δ_rG −72.4 kJ/mol K 4.83 × 10¹² pK −12.68: CaCl₂Crystalline solid + Rb₂SO₄Crystalline solid
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CaSO₄↓Crystalline solidinsoluble, anhydrite + 2RbClCrystalline solid

	Standard enthalpy of reaction Δ_rH° kJ · mol⁻¹	Standard Gibbs energy of reaction Δ_rG° kJ · mol⁻¹	Standard entropy of reaction Δ_rS° J · K⁻¹ · mol⁻¹	Standard heat capacity of reaction at constant pressure Δ_rC_p° J · K⁻¹ · mol⁻¹
per 1 mol of Equation	−73.4	−72.4	−3.5	−2.23
per 1 mol of Calcium chloride	−73.4	−72.4	−3.5	−2.23
per 1 mol of Rubidium sulfate	−73.4	−72.4	−3.5	−2.23
per 1 mol of Calcium sulfate	−73.4	−72.4	−3.5	−2.23
per 1 mol of Rubidium chloride	−36.7	−36.2	−1.8	−1.11

Changes in standard condition (2)

Reaction of calcium chloride and rubidium sulfate ◆ Δ_rG −64.0 kJ/mol K 1.63 × 10¹¹ pK −11.21: CaCl₂Crystalline solid + Rb₂SO₄Crystalline solid
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CaSO₄↓Crystalline solidsoluble, α + 2RbClCrystalline solid

	Standard enthalpy of reaction Δ_rH° kJ · mol⁻¹	Standard Gibbs energy of reaction Δ_rG° kJ · mol⁻¹	Standard entropy of reaction Δ_rS° J · K⁻¹ · mol⁻¹	Standard heat capacity of reaction at constant pressure Δ_rC_p° J · K⁻¹ · mol⁻¹
per 1 mol of Equation	−64.5	−64.0	−1.8	−1.68
per 1 mol of Calcium chloride	−64.5	−64.0	−1.8	−1.68
per 1 mol of Rubidium sulfate	−64.5	−64.0	−1.8	−1.68
per 1 mol of Calcium sulfate	−64.5	−64.0	−1.8	−1.68
per 1 mol of Rubidium chloride	−32.3	−32.0	−0.90	−0.840

Changes in standard condition (3)

Reaction of calcium chloride and rubidium sulfate ◆ Δ_rG −59.6 kJ/mol K 2.76 × 10¹⁰ pK −10.44: CaCl₂Crystalline solid + Rb₂SO₄Crystalline solid
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CaSO₄↓Crystalline solidsoluble, β + 2RbClCrystalline solid

	Standard enthalpy of reaction Δ_rH° kJ · mol⁻¹	Standard Gibbs energy of reaction Δ_rG° kJ · mol⁻¹	Standard entropy of reaction Δ_rS° J · K⁻¹ · mol⁻¹	Standard heat capacity of reaction at constant pressure Δ_rC_p° J · K⁻¹ · mol⁻¹
per 1 mol of Equation	−60.1	−59.6	−1.8	−2.85
per 1 mol of Calcium chloride	−60.1	−59.6	−1.8	−2.85
per 1 mol of Rubidium sulfate	−60.1	−59.6	−1.8	−2.85
per 1 mol of Calcium sulfate	−60.1	−59.6	−1.8	−2.85
per 1 mol of Rubidium chloride	−30.1	−29.8	−0.90	−1.43

Changes in aqueous solution (1)

Reaction of calcium chloride and rubidium sulfate ◆ Δ_rG −23.68 kJ/mol K 1.41 × 10⁴ pK −4.15: CaCl₂Ionized aqueous solution + Rb₂SO₄Ionized aqueous solution
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CaSO₄↓Crystalline solidinsoluble, anhydrite + 2RbClIonized aqueous solution

	Standard enthalpy of reaction Δ_rH° kJ · mol⁻¹	Standard Gibbs energy of reaction Δ_rG° kJ · mol⁻¹	Standard entropy of reaction Δ_rS° J · K⁻¹ · mol⁻¹	Standard heat capacity of reaction at constant pressure Δ_rC_p° J · K⁻¹ · mol⁻¹
per 1 mol of Equation	17.98	−23.68	139.7	–
per 1 mol of Calcium chloride	17.98	−23.68	139.7	–
per 1 mol of Rubidium sulfate	17.98	−23.68	139.7	–
per 1 mol of Calcium sulfate	17.98	−23.68	139.7	–
per 1 mol of Rubidium chloride	8.990	−11.84	69.85	–

Changes in aqueous solution (2)

Reaction of calcium chloride and rubidium sulfate ◆ Δ_rG −15.31 kJ/mol K 4.81 × 10² pK −2.68: CaCl₂Ionized aqueous solution + Rb₂SO₄Ionized aqueous solution
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CaSO₄↓Crystalline solidsoluble, α + 2RbClIonized aqueous solution

	Standard enthalpy of reaction Δ_rH° kJ · mol⁻¹	Standard Gibbs energy of reaction Δ_rG° kJ · mol⁻¹	Standard entropy of reaction Δ_rS° J · K⁻¹ · mol⁻¹	Standard heat capacity of reaction at constant pressure Δ_rC_p° J · K⁻¹ · mol⁻¹
per 1 mol of Equation	26.85	−15.31	141.4	–
per 1 mol of Calcium chloride	26.85	−15.31	141.4	–
per 1 mol of Rubidium sulfate	26.85	−15.31	141.4	–
per 1 mol of Calcium sulfate	26.85	−15.31	141.4	–
per 1 mol of Rubidium chloride	13.43	−7.655	70.70	–

Changes in aqueous solution (3)

Reaction of calcium chloride and rubidium sulfate ◆ Δ_rG −10.87 kJ/mol K 8.02 × 10¹ pK −1.90: CaCl₂Ionized aqueous solution + Rb₂SO₄Ionized aqueous solution
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CaSO₄↓Crystalline solidsoluble, β + 2RbClIonized aqueous solution

	Standard enthalpy of reaction Δ_rH° kJ · mol⁻¹	Standard Gibbs energy of reaction Δ_rG° kJ · mol⁻¹	Standard entropy of reaction Δ_rS° J · K⁻¹ · mol⁻¹	Standard heat capacity of reaction at constant pressure Δ_rC_p° J · K⁻¹ · mol⁻¹
per 1 mol of Equation	31.29	−10.87	141.4	–
per 1 mol of Calcium chloride	31.29	−10.87	141.4	–
per 1 mol of Rubidium sulfate	31.29	−10.87	141.4	–
per 1 mol of Calcium sulfate	31.29	−10.87	141.4	–
per 1 mol of Rubidium chloride	15.64	−5.435	70.70	–

Thermodynamic data of reactants

Chemical formula	Standard enthalpy of formation Δ_fH° kJ · mol⁻¹	Standard Gibbs energy of formation Δ_fG° kJ · mol⁻¹	Standard molar entropy S° J · K⁻¹ · mol⁻¹	Standard molar heat capacity at constant pressure C_p° J · K⁻¹ · mol⁻¹
CaCl₂ (cr)	-795.8^[1]	-748.1^[1]	104.6^[1]	72.59^[1]
CaCl₂ (g)	-471.5^[1]	-479.24^[1]	290.27^[1]	59.33^[1]
CaCl₂ (ai)	-877.13^[1]	-816.01^[1]	59.8^[1]	–
CaCl₂ (cr) 1 hydrate	-1109.2^[1]	–	–	–
CaCl₂ (cr) 2 hydrate	-1402.9^[1]	–	–	–
CaCl₂ (cr) 4 hydrate	-2009.6^[1]	–	–	–
CaCl₂ (cr) 6 hydrate	-2607.9^[1]	–	–	–
Rb₂SO₄ (cr)	-1435.61^[1]	-1316.89^[1]	197.44^[1]	134.06^[1]
Rb₂SO₄ (g)	-1068.6^[1]	–	–	–
Rb₂SO₄ (ai)	-1411.60^[1]	-1312.50^[1]	263.2^[1]	–

* (cr):Crystalline solid, (g):Gas, (ai):Ionized aqueous solution

Thermodynamic data of products

Chemical formula	Standard enthalpy of formation Δ_fH° kJ · mol⁻¹	Standard Gibbs energy of formation Δ_fG° kJ · mol⁻¹	Standard molar entropy S° J · K⁻¹ · mol⁻¹	Standard molar heat capacity at constant pressure C_p° J · K⁻¹ · mol⁻¹
CaSO₄ (cr) insoluble, anhydrite	-1434.11^[1]	-1321.79^[1]	106.7^[1]	99.66^[1]
CaSO₄ (cr) soluble, α	-1425.24^[1]	-1313.42^[1]	108.4^[1]	100.21^[1]
CaSO₄ (cr) soluble, β	-1420.80^[1]	-1308.98^[1]	108.4^[1]	99.04^[1]
CaSO₄ (ai)	-1452.10^[1]	-1298.10^[1]	-33.1^[1]	–
CaSO₄ (cr) 0.5 hydrate macrocrystalline, α	-1576.74^[1]	-1436.74^[1]	130.5^[1]	119.41^[1]
CaSO₄ (cr) 0.5 hydrate microcrystalline, β	-1574.65^[1]	-1435.78^[1]	134.3^[1]	124.22^[1]
CaSO₄ (cr) 2 hydrate selenite	-2022.63^[1]	-1797.28^[1]	194.1^[1]	186.02^[1]
RbCl (cr)	-435.35^[1]	-407.80^[1]	95.90^[1]	52.38^[1]
RbCl (g)	-228.9^[1]	-247.3^[1]	249.56^[1]	36.82^[1]
RbCl (ai)	-418.32^[1]	-415.20^[1]	177.99^[1]	–

* (cr):Crystalline solid, (ai):Ionized aqueous solution, (g):Gas

References

List of references

1
Janiel J. Reed (1989)
The NBS Tables of Chemical Thermodynamic Properties: Selected Values for Inorganic and C1 and C2 Organic Substances in SI Units
https://doi.org/10.18434/M32124
National Institute of Standards and Technology (NIST)
Citation list

Δ_rG	−72.4 kJ/mol
K	4.83 × 10¹²
pK	−12.68

Δ_rG	−64.0 kJ/mol
K	1.63 × 10¹¹
pK	−11.21

Δ_rG	−59.6 kJ/mol
K	2.76 × 10¹⁰
pK	−10.44

Δ_rG	−23.68 kJ/mol
K	1.41 × 10⁴
pK	−4.15

CaCl2 + Rb2SO4 💧→ CaSO4↓ + 2RbCl

Reaction data

Chemical equation

General equation

Oxidation state of each atom