Micah Manners ran at the woman bare-chested and sprayed the liquid at the shocked victim during the incident outside the store in Gipton, Leeds.
Manners, 37, also shouted vile racial abuse at the woman during the incident.
The victim felt itching to her eyes, a burning sensation to her nose and feared that acid had been thrown over her.
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Firefighters were contacted and a hazmat team was also deployed following the incident on June 29, 2019.
Manners appeared before Leeds Crown Court after pleading guilty to an offence of administering a noxious substance with intent to injure, aggrieve or annoy.
Howard Shaw, prosecuting, said the victim was in her car with her two-year-old son outside the store on Amberton Road as she waited for her husband.
She sounded the horn of her Renault Megan due to the length of time her husband was spending inside the store.
Mr Shaw said Manners was a passenger in a car parked nearby and mistakenly believed the woman had sounded the horn at him.
The mum then asked the driver of the car to tell Manners to stop shouting as she had her son with her.
The prosecutor said: "The defendant got out and shouted more racial abuse in an aggressive manner.
"He was bare-chested and shouted 'go back to your own country, you are not even British.'"
Manners, of Jackie Smart Court, Chapeltown, returned to the car and the vehicle was driven away.
The prosecutor continued: "The complainant felt shocked and angry about what had happened and was holding a bottle of water.
"As the defendant's car passed, unfortunately, she threw some of the water from her bottle at the car and began to attend to her son in her own car."
The other car then pulled up nearby.
Manners got out and took a large bottle of antifreeze from the boot.
The woman felt itching to her eyes and a burning sensation to her nose. She was taken to hospital, fearing she had been attacked with acid.
Mr Shaw added: "The fire brigade was called and a hazmat team was called by the police who ascertained it was antifreeze."
A witness described seeing Manners shouting racial abuse and throwing a pink liquid over the victim.
Jessica Strange, mitigating, said Manners was sorry and ashamed of the way he behaved and had struggled to come to terms with what he had done.
She said: "As a black man who on many occasions has received racial abuse, he knows how extremely upsetting it is.
"He used those words in order to cause offence.
"He is extremely remorseful about what he said.
"He should not have retaliated in the way he did and he has accepted responsibility by his guilty plea."
Manners was given an 12-month sentence, suspended for 18 months, plus 240 hours of unpaid work.
Sentencing, Recorder Darren Preston said: "What I find difficult is not only how anyone can use words like you used, but how a man who has himself suffered racist abuse could use that language.
"Questioning her nationality on no evidence at all and referring to the colour of her skin. You know the pain it causes."