Gas evolution arrow

An upward arrow after a formula, marking a gas leaving the reaction.

Also known as: Up arrow chemistry, Effervescence arrow

ScientificStandard profile

Meanings

An upward arrow after a formula means that product escapes as a gas. It and the precipitate arrow are the same convention pointing two ways, and both describe leaving the solution rather than the reaction.

Common modern usageVerified fact
Marks a product that leaves the reaction mixture as a gas.
Contexts: Laboratory
Common modern usageVerified fact
Describes leaving the solution rather than leaving the reaction, which is why the substance still appears in the equation.
Contexts: Laboratory

Visual description

A short vertical arrow pointing upward, set immediately after a chemical formula on the same line.

Symmetry: vertical
Orientation: upright

Opposite of: Precipitate arrow
Gas leaving upward against solid falling down.

Confidence

IdentityHigh confidence: High confidence because the identity is documented in encyclopedic references.
Historical originModerate confidence: Moderate confidence because the historical origin is documented in encyclopedic references, but early or supporting evidence is limited, but the regional or cultural match to this specific claim is not precise.
Current useHigh confidence: High confidence because the current use is documented in encyclopedic references.
Visual matchHigh confidence: High confidence because the visual match is documented in encyclopedic references.

Sources

Precipitation (chemistry)
Wikipedia · retrieved 2026-08-01
Tertiary reference. Used for what a symbol denotes in ordinary scientific practice and for which fields reuse it, never for a claim that any body assigns the letter its meaning.
Chemical equation
Wikipedia · retrieved 2026-08-01
Tertiary reference. Used for what a symbol denotes in ordinary scientific practice and for which fields reuse it, never for a claim that any body assigns the letter its meaning.

Last reviewed 2026-07-31

Part of

Chemical equation and structure notation

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Meanings

Common modern usageVerified fact

Marks a product that leaves the reaction mixture as a gas.

Contexts: Laboratory

Common modern usageVerified fact

Describes leaving the solution rather than leaving the reaction, which is why the substance still appears in the equation.

Contexts: Laboratory

Confidence

IdentityHigh confidence: High confidence because the identity is documented in encyclopedic references.
Historical originModerate confidence: Moderate confidence because the historical origin is documented in encyclopedic references, but early or supporting evidence is limited, but the regional or cultural match to this specific claim is not precise.
Current useHigh confidence: High confidence because the current use is documented in encyclopedic references.
Visual matchHigh confidence: High confidence because the visual match is documented in encyclopedic references.

Sources

Precipitation (chemistry)
Wikipedia · retrieved 2026-08-01
Tertiary reference. Used for what a symbol denotes in ordinary scientific practice and for which fields reuse it, never for a claim that any body assigns the letter its meaning.
Chemical equation
Wikipedia · retrieved 2026-08-01
Tertiary reference. Used for what a symbol denotes in ordinary scientific practice and for which fields reuse it, never for a claim that any body assigns the letter its meaning.

Last reviewed 2026-07-31

Meanings

Visual description

Related & commonly confused symbols

Meanings

Visual description

Related & commonly confused symbols